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Micro-Nano Optics and Its Applications
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Micro-Nano Optics and Its Applications

A special issue of Coatings (ISSN 2079-6412). This special issue belongs to the section "Surface Engineering for Energy Harvesting, Conversion, and Storage".

Deadline for manuscript submissions: closed (31 December 2023) | Viewed by 51745

Special Issue Editors

Prof. Dr. Zao Yi

E-Mail Website
Guest Editor
Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology, Mianyang 621010, China
Interests: metamaterials; plasmonics; functional nanomaterials; micro/nano-optics; solar cell; photothermal effect; Raman enhancement effect; photocatalysis
Prof. Dr. Chao Liu

E-Mail Website
Guest Editor
Northeast Petroleum University
Interests: applications of local surface plasmon resonance of nanoparticles, nano-photonics, photonic crystal fiber sensors based on surface plasmon resonance in bio-sensing fields.

Special Issue Information

Dear Colleagues,

Micro/nano-optics is one of the most active frontiers in the development of optics. It combines the frontier achievements of photonics and nanotechnology. Its main advantage is that it can realize many new functions on the basis of local electromagnetic interaction. It has become an indispensable key science and technology in the 21st century. Micro/nano-optics is not only one of the frontier research directions in the optical field, but also an important direction of development for new optoelectronic industries. It plays an irreplaceable role in optical communication, optical interconnection, optical storage, sensing imaging, sensing measurement, display, solid-state lighting, biomedicine, security, green energy, and other fields.

The rapid growth of micro/nano-optics has benefited from the continuous quest to design and build innovative nanostructures. At present, there is a strong interest in exploring the unconventional properties and advantages offered by alternative plasmonic nanostructures (beyond noble metals), high or giant refractive index nanostructures, perovskite nanostructures, quantum confined nanostructures (two-dimensional or three-dimensional), and hybrid nanostructures.

In this Special Issue, we aim to provide a timely perspective on the advances in micro/nano-optics related to such novel nanostructures. Topics to be covered include (but are not limited to) the following:

  • Fabrication of nanostructures;
  • Optical properties of nanostructures;
  • Nanostructured metamaterials: fabrication and optical properties;
  • Biosensing based on surface plasmon resonance;
  • Interaction between laser and matter;
  • Applications, e.g., sensing, photocatalysis, photovoltaics, lighting, and switching.

Prof. Dr. Zao Yi
Prof. Dr. Chao Liu
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Nanostructures
  • Metamaterials
  • Micro/nano-optics
  • Plasmonics
  • Applications of micro/nano-optics

Published Papers (30 papers)

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Research

12 pages, 887 KiB  
Article
Intelligent Space Thermal Control Radiator Based on Phase Change Material with Partial Visible Transparency
by Xianghao Kong, Hezhi Sun, Shiri Liang, Zao Yi, Naiting Gu and Yougen Yi
Coatings 2024, 14(5), 535; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings14050535 - 25 Apr 2024
Viewed by 267
Abstract
Coating structures with dynamically adjustable infrared emissivity are crucial in spacecraft components to cope with the transient thermal environments of space. For a long time, thermochromic phase change materials have been widely used in applications requiring emissivity adjustment, and optimizing the range of [...] Read more.
Coating structures with dynamically adjustable infrared emissivity are crucial in spacecraft components to cope with the transient thermal environments of space. For a long time, thermochromic phase change materials have been widely used in applications requiring emissivity adjustment, and optimizing the range of adjustable infrared emissivity has always been at the forefront of research. However, reducing the absorption of solar radiation has significant implications for the practical application and thermal stability of spacecraft components in space environments. In this paper, we propose a multilayer film structure based on the phase change material VO2 combined with the materials ZnSe and ITO to achieve low solar radiation absorption and adjustable infrared emissivity for intelligent thermal radiators in space. Through finite element simulation analysis of the structure, we achieve a solar radiation absorption rate of 0.3 and an adjustable infrared emissivity of 0.49. According to Stefan–Boltzmann’s law, the structure exhibits strong radiative heat dissipation at high temperatures and weak energy dissipation at low temperatures to maintain the thermal stability of the device and ensure efficient operation. The intelligent thermal radiator operates based on the principles of Fabry–Perot resonance. Therefore, the multilayer structure based on the phase change material VO2 demonstrates excellent performance in both solar radiation absorption and adjustable infrared emissivity, showcasing its tremendous potential in the field of intelligent thermal control in aerospace. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
13 pages, 3842 KiB  
Article
Temperature-Controlled and Adjustable Terahertz Device Based on Vanadium Dioxide
by Wenqiang Lu, Hao Sun, Wenjing Xuan, Yanyan Ding and Yougen Yi
Coatings 2024, 14(4), 478; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings14040478 - 13 Apr 2024
Viewed by 386
Abstract
We propose a simple multifunctional terahertz absorber based on the simulation. The device consists of a gold layer, a SiO2 dielectric layer, and a VO2 top layer. The modulation mechanism of this device is to utilize the thermally induced phase transition [...] Read more.
We propose a simple multifunctional terahertz absorber based on the simulation. The device consists of a gold layer, a SiO2 dielectric layer, and a VO2 top layer. The modulation mechanism of this device is to utilize the thermally induced phase transition characteristics of vanadium dioxide material. The simulation results show that when the temperature is 312 K, the device has the effect of complete reflection of terahertz waves. When the temperature is 345 K, the device has almost perfect absorption of terahertz wave in the range of 4.7–9.7 THz, and the spectral absorptivity is modulated in the range of 0~0.999. The electric field conditions at different temperatures were plotted to further explain the reasons for the performance transition of the device. The terahertz device was explained using impedance matching theory. In addition, the influence of different structural parameters on absorption rate was studied, providing reference for practical applications. At the same time, the device is polarization-insensitive and insensitive to the incident angle. When the incident angle changes from 0°to 45°, the device still has a stable absorption effect. The device has great application prospects in terahertz stealth, modulation, and other fields and provides ideas for the design of related devices. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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12 pages, 34895 KiB  
Article
Ultra-High-Sensitivity and -Stability Thin-Film Heat Flux Sensor Based on Transverse Thermoelectric Effect
by Hao Chen, Yong Wang, Zao Yi, Bo Dai, Bin Tang, Xibin Xu and Yougen Yi
Coatings 2023, 13(9), 1610; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings13091610 - 14 Sep 2023
Cited by 7 | Viewed by 1141
Abstract
In this study, we investigate the sensitivity properties of YBa2Cu3O7-δ thin films with a 15° tilting angle in relation to heat flux density. The films were prepared using the laser pulsed deposition (PLD) technique, and their characteristics were [...] Read more.
In this study, we investigate the sensitivity properties of YBa2Cu3O7-δ thin films with a 15° tilting angle in relation to heat flux density. The films were prepared using the laser pulsed deposition (PLD) technique, and their characteristics were evaluated using various techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM), and infrared steady-state and laser transient calibration systems. The YBa2Cu3O7-δ films prepared in this study were found to be of good quality, exhibiting a single-phase structure with strict (001) orientation. Both the substrate and film diffraction peaks were sharp and consistent with the step-flow growth mode, indicating high crystalline quality. Ultra-high sensitivity in the range of 0 to 100 kW/m2, the maximum sensitivity is 230 μV/(kW/m2), and an uncertainty is only 3%. According to the infrared steady-state heat flux calibration system test, when the single output power of the quartz lamp array is 0.2 kW, 0.3 kW, 0.4 kW and 0.5 kW, the maximum output voltage is 0.19 mV, 0.41 mV, 0.63 mV and 0.94 mV, respectively, indicating that the output voltage of the sensor increases with the increase in heat flux, showing a good linear characteristic, and the fitting linearity is 0.99. Through the test of the laser transient thermal current calibration system, the sensors are found to have excellent response–recovery characteristics at 500 kHz and 1000 kHz fiber laser frequencies, and the maximum voltage output is 8.83 mV and 9.09 mV, respectively. Moreover, the component has excellent repeatability, and the maximum measurement error is only 1.94%. Our findings demonstrate the potential of YBa2Cu3O7-δ thin films for use in heat flux sensing applications. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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13 pages, 5047 KiB  
Article
Active Broadband Absorber Based on Phase-Change Materials Optimized via Evolutionary Algorithm
by Jing Ma, Yonghong Tian, Jingyi Cheng, Shubo Cheng, Bin Tang, Jing Chen, Yougen Yi, Pinghui Wu, Zao Yi and Tangyou Sun
Coatings 2023, 13(9), 1604; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings13091604 - 14 Sep 2023
Cited by 28 | Viewed by 1172
Abstract
This article proposes a temperature-controlled absorber based on VO2, which consists of five layers: a disk-shaped VO2 layer array, a dielectric layer, a circular hole VO2 array, a SiO2 layer, and a gold substrate from top to bottom. [...] Read more.
This article proposes a temperature-controlled absorber based on VO2, which consists of five layers: a disk-shaped VO2 layer array, a dielectric layer, a circular hole VO2 array, a SiO2 layer, and a gold substrate from top to bottom. We optimized the thickness of the other four layers of the absorber, except for the gold layer, using PSO. After ten iterations, we determined that the optimal parameters for the top-to-bottom four-layer thicknesses were 0.183 μm, 0.452 μm, 0.557 μm and 1.994 μm. At this point, our absorber reached the optimal absorption parameters, and we plotted the absorption spectrum under these conditions. We found that the absorption rate at 29.1–47.2 THz was higher than 90%, and the absorption bandwidth was as high as 18.1 THZ. This frequency band covers most of the atmospheric window area (23–37.5 THz), so it will have good practicality. At 30.8 THz and 43.12 THz, there were perfect absorption peaks with absorption rates of 99.99% and 99.99%, respectively. We explained the cause of absorption from the perspective of electric field, and then we studied the change in the absorption curve of the absorber when the temperature of VO2 changed, and we can directly observe the changes in the electric field to explain this. Finally, we can tune the bandwidth and absorption rate of the absorber by changing the structure of the VO2 pattern. After comparing with other absorbers developed in recent years, our absorber still has good competitiveness, and we believe that our solution is expected to have outstanding performance in fields such as photothermal conversion and thermal stealth in the future. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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19 pages, 9000 KiB  
Article
Study on the Effects and Mechanism of Temperature and AO Flux Density in the AO Interaction with Upilex-S Using the ReaxFF Method
by Shiying Qiao, Haifu Jiang, Ruiqiong Zhai, Yuming Liu, Tao Li, Yanlin Xu and Lixiang Jiang
Coatings 2023, 13(9), 1586; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings13091586 - 12 Sep 2023
Viewed by 715
Abstract
Atomic oxygen (AO), which is one of the most predominant and conspicuous space environmental factors in the low earth orbit, leads to severe deterioration of polymeric materials in spacecraft. The AO flux density and ambient temperature vary while a craft orbits in space; [...] Read more.
Atomic oxygen (AO), which is one of the most predominant and conspicuous space environmental factors in the low earth orbit, leads to severe deterioration of polymeric materials in spacecraft. The AO flux density and ambient temperature vary while a craft orbits in space; thus, it is necessary to pay close attention to the flux density and temperature effects on the mechanism of the AO interaction with materials. In past years, polyimide has been widely used on spacecraft due to its excellent performance—that is the reason why we chose Upilex-S as the object for study. It was analyzed using the ReaxFF reactive force field molecular dynamics simulation, respectively from the aspect of impact-induced temperature variation, mass loss, reaction product and erosion yield. The results show that dense AO deposition on the surface impedes further erosion at low temperatures, and the AO interaction with Upilex-S is exacerbated as the ambient temperature increases. However, the accelerating rate is inversely proportional to the ambient temperature, which means the higher the ambient temperature is, the slower it increases. On the other hand, the interaction rate of AO induced to Upilex-S is aggravated as the flux density increases at the lower stage, while the interaction rate begins to drop as the flux density increases at the higher level. The AO erosion effect is a complicated process rather than a simple summation of single atomic oxygen interactions. Our study could be used as a technical reference for the wide usage of Upilex-S on spacecraft. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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14 pages, 6829 KiB  
Article
Design of a New Type of In-Hole Gold-Coated High-Performance Quasi-PCF Sensor Enhanced with Surface Plasmon Resonance
by Wenjun Zhou, Xi Qin, Ming Lv, Lifeng Qiu, Zhongjiang Chen and Fan Zhang
Coatings 2023, 13(7), 1261; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings13071261 - 18 Jul 2023
Cited by 5 | Viewed by 1150
Abstract
With the development of aerospace, deep-sea exploration and other technologies, the demand for anti-electromagnetic, high-sensitivity and miniaturized sensors is increasingly urgent. In this paper, a model of a quasi-photonic crystal fiber (Q-PCF) refractive index (RI) sensor enhanced with surface plasmon resonance (SPR) is [...] Read more.
With the development of aerospace, deep-sea exploration and other technologies, the demand for anti-electromagnetic, high-sensitivity and miniaturized sensors is increasingly urgent. In this paper, a model of a quasi-photonic crystal fiber (Q-PCF) refractive index (RI) sensor enhanced with surface plasmon resonance (SPR) is proposed. A stable gold film with a significant SPR effect is applied to the two identically sized and oppositely positioned air holes of the proposed sensor, and all air holes are filled with analyte. A detailed analysis of the mode characteristics, structural parameters and RI sensing performance of the sensor has been carried out using the finite element method. It has been shown that the maximum sensitivity (S) is 4977.59 nm/RIU in the RI range of 1.35–1.40, corresponding to a resolution (R) of 2.01 × 10−5 RIU and a figure of merit (FOM) of 160.36 RIU−1. The proposed Q-PCF sensor has unique fabrication advantages and outstanding sensing properties, providing a new idea for biosensing, complex environment monitoring and long-range measurement, and is of great practical value in the field of highly integrated sensing. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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14 pages, 4709 KiB  
Article
Enhancement of Photoelectric Performance Based on Ultrathin Wide Spectrum Solar Absorption in Cruciform Microstructure Germanium Solar Cells
by Ziyou Zhou, Wenfeng Liu, Hailong Huang, Xiaolong Ding and Xintian Li
Coatings 2023, 13(6), 1123; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings13061123 - 19 Jun 2023
Cited by 4 | Viewed by 1249
Abstract
In this paper, the solar absorption level of PEDOT:PSS/Ge organic and inorganic hybrid solar cells (HSCs) with different parameters of cruciform microstructure (CM) is studied, using the finite-difference time domain (FDTD) method. The light absorption in HSCs with CM is above 90% in [...] Read more.
In this paper, the solar absorption level of PEDOT:PSS/Ge organic and inorganic hybrid solar cells (HSCs) with different parameters of cruciform microstructure (CM) is studied, using the finite-difference time domain (FDTD) method. The light absorption in HSCs with CM is above 90% in the range of 300 nm to 1300 nm. Under the AM1.5 solar spectrum, the average absorptivity of solar energy is also at a very high level. At the same time, we use DEVICE software to calculate the electrical properties, such as the open-circuit voltage (Voc), short-circuit current density (Jsc), and maximum power density (Pmax). The electrical simulation results show that the Pmax of HSCs with CM improves to 72.16% from the planar HSCs. Besides, in order to study the mechanism of solar energy absorption in HSCs containing CM, the logarithmic plots of electric field intensity of HSCs with CM and planar HSCs, are analyzed at different wavelengths. The work shows that the CM shows an excellent light-trapping effect, which reduces the surface reflectivity of HSCs, and greatly improves the photoelectric conversion efficiency of Ge solar cells. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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12 pages, 8536 KiB  
Article
Achieving Ultralow-Density, High-Purity Au Foam Hohlraum with Hierarchical Porous Structure
by Xiulan Tan, Jian Wang, Jiangshan Luo, Gao Niu and Chaoyang Wang
Coatings 2023, 13(5), 888; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings13050888 - 08 May 2023
Viewed by 1061
Abstract
High Z (atomic number) metallic foams with a low density and high purity are urgent demands in high energy-density physical experiments. They suppress plasma expansion and convert the laser pulses to X-rays more uniformly and efficiently. Thus, we synthesized an ultralow-density and high-purity [...] Read more.
High Z (atomic number) metallic foams with a low density and high purity are urgent demands in high energy-density physical experiments. They suppress plasma expansion and convert the laser pulses to X-rays more uniformly and efficiently. Thus, we synthesized an ultralow-density and high-purity Au foam hohlraum with a hierarchical porous structure via a template-dealloying method in this paper. Silica (SiO2) beads were introduced as the sacrificial templates due to their high stability at an elevated temperature. The Au and Ag nanoparticles were successively deposited onto the SiO2 templates via an electroless deposition process to form an Ag@Au@SiO2 core-shell structure. Cylindrical Ag@Au@SiO2 hohlraum was achieved using a filter-casting technique with a patented mold. Afterward, an Au-Ag alloy was generated during 36 h of calcination at 400 °C. Self-supported Au foam hohlraum with the hierarchical porous structure was gained after the SiO2 templates were removed, followed by the dealloying of the Ag from the Au-Ag alloy. A self-supporting Au foam hohlraum with a density as low as 0.2 g/cm3 and a purity of 99.37% was achieved, and the density decreased by about 44.5% when compared with our previous Au foam (density: 0.36 g/cm3, purity: less than 96%) using microspherical polystyrene as the sacrificial template. Thus, the ultralow-density, high-purity Au foam hohlraum may exhibit profound application in high-energy physical experiments in the near future. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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14 pages, 3950 KiB  
Article
Anchoring Monodispersed NiSe@Ni Particles on Graphene for Energy Storage in Supercapacitors
by Xianbin Xiao, Fangzhou Jin, Zhongsheng Pu, Peng Zhu, Zhiqiang Wei, Hua Yang and Jinlong Jiang
Coatings 2023, 13(5), 885; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings13050885 - 08 May 2023
Cited by 1 | Viewed by 1164
Abstract
In this study, monodispersed NiSe@Ni particles were successfully anchored on graphene sheets by electroless nickel plating combined with a chemical-vapor-reaction process, in which the nickel particles were first deposited onto graphene sheets and subsequently transformed in situ into NiSe@Ni at an elevated temperature. [...] Read more.
In this study, monodispersed NiSe@Ni particles were successfully anchored on graphene sheets by electroless nickel plating combined with a chemical-vapor-reaction process, in which the nickel particles were first deposited onto graphene sheets and subsequently transformed in situ into NiSe@Ni at an elevated temperature. The obtained product showed a unique multi-dimensional coupling structure, namely, monodispersed NiSe@Ni particles (0 D) anchored on graphene sheets (2 D), which enabled maximum synergy on the specific surface area, conductivity, and the electrochemical activity of NiSe, Ni, and graphene multi-phases. The NiSe@Ni/graphene composite showed a specific capacity of 302 mAh g−1 at a current density of 1 A g−1 in a potassium-hydroxide-electrolyte solution. Meanwhile, the hybrid supercapacitor of NiSe@Ni/graphene//AC exhibited a high energy density of 68.0 Wh kg−1 at 803.0 W kg−1 and maintained 72.53% of the initial capacity after 10,000 cycles at a current density of 10 A g−1. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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10 pages, 6646 KiB  
Article
3D Multilayered Metamaterials with High Plasmonic Hotspot Density for Surface—Enhanced Raman Spectroscopy
by Jun Chen, Chai Zhang, Feng Tang, Xin Ye, Yubin Zhang, Jingjun Wu, Kaixuan Wang, Ning Zhang and Liming Yang
Coatings 2023, 13(5), 844; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings13050844 - 28 Apr 2023
Viewed by 1065
Abstract
Three-dimensional (3D) plasmonic metamaterials have become a trend in the application of nanophotonic devices. In this paper, a convenient and inexpensive method for the design of 3D multilayer plasmonic metamaterials is constructed using a one-step self-shielded reactive-ion-etching process (OSRP) and a thermal evaporation [...] Read more.
Three-dimensional (3D) plasmonic metamaterials have become a trend in the application of nanophotonic devices. In this paper, a convenient and inexpensive method for the design of 3D multilayer plasmonic metamaterials is constructed using a one-step self-shielded reactive-ion-etching process (OSRP) and a thermal evaporation system, which provides an efficient and low-cost method for the preparation of surface-enhanced Raman spectroscopy (SERS) substrates. The near-field enhancement of the 3D plasmonic metamaterials provides highly efficient electromagnetic resonance, and highly sensitive and uniform SERS sensing capabilities. The SERS detection results of rhodamine B (Rh. B) and rhodamine 6G (R6G) on this substrate show that the detection limit could reach 10–13 mol/L, and the signal could give expression to excellent uniform stability. The results show that high sensitivity and high robustness SERS substrates can be prepared with high efficiency and low cost. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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15 pages, 6250 KiB  
Article
High Absorptivity and Ultra-Wideband Solar Absorber Based on Ti-Al2O3 Cross Elliptical Disk Arrays
by Yuanjian Zhang, Yingting Yi, Wenxin Li, Shiri Liang, Jing Ma, Shubo Cheng, Wenxing Yang and Yougen Yi
Coatings 2023, 13(3), 531; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings13030531 - 28 Feb 2023
Cited by 53 | Viewed by 1896
Abstract
Perfect metamaterial absorbers have attracted researchers’ attention in solar energy harvesting and utilization. An ideal solar absorber should provide high absorption, be ultra-wideband, and be insensitive to polarization and incident angles, which brings challenges to research. In this paper, we proposed and optimized [...] Read more.
Perfect metamaterial absorbers have attracted researchers’ attention in solar energy harvesting and utilization. An ideal solar absorber should provide high absorption, be ultra-wideband, and be insensitive to polarization and incident angles, which brings challenges to research. In this paper, we proposed and optimized an ultra-wideband solar absorber based on Ti-Al2O3 cross elliptical disk arrays to obtain the ultra-wideband absorption of solar energy. The addition of a cavity greatly improves the energy-absorbing effect in the operating band, which has research value. The absorption spectrum and field distribution were analyzed by the finite difference time domain method. For the physical mechanism, the electric and magnetic field distribution indicates that ultra-wideband absorption is caused by propagation surface plasmon resonance (SPR), localized SPR and Fabry–Perot (F-P) resonance excited between Ti and Al2O3 disks. The results demonstrate that the absorption bandwidth with the absorption rate beyond 90% reaches 1380 nm (385–1765 nm), and the average absorption reaches an astonishing 98.78%. The absorption bandwidth matches the main radiation bandwidth of the solar energy, which is approximately 295–2500 nm according to the data from the literature, and the total thickness of the structure is only 445 nm. Moreover, the ultra-wideband solar absorber is insensitive to the polarization angle and oblique incidence angle. The proposed ultra-wideband solar absorber has research and application value in solar energy harvesting, photothermal conversion and utilization. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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11 pages, 1998 KiB  
Article
Patterned Graphene-Based Metamaterials for Terahertz Wave Absorption
by Siyuan Zhou, Kaixi Bi, Qiannan Li, Linyu Mei, Yaokai Niu, Wenxiao Fu, Shuqi Han, Shuai Zhang, Jiliang Mu, Ligang Tan, Wenping Geng and Xiujian Chou
Coatings 2023, 13(1), 59; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings13010059 - 29 Dec 2022
Cited by 12 | Viewed by 2243
Abstract
Graphene-based metamaterials have been widely applied in optoelectronic devices, optical modulators, and chemical sensors due to the outstanding tunability and optical response in the terahertz (THz) region. Here, tunable THz metamaterial absorbers based on patterned graphene are designed, fabricated, and modulated. The proposed [...] Read more.
Graphene-based metamaterials have been widely applied in optoelectronic devices, optical modulators, and chemical sensors due to the outstanding tunability and optical response in the terahertz (THz) region. Here, tunable THz metamaterial absorbers based on patterned graphene are designed, fabricated, and modulated. The proposed metamaterial absorbers are constructed by the top layer of patterned graphene arrays and the aluminum (Al) film separated by polyimide (PI). The different THz absorption spectra can be acquired by changing the patterns of graphene. In order to verify the simulation results, a series of tests were conducted by THz time-domain spectrometer (THz-TDS) systems. The proposed absorbers are able to be insensitive to the angle of the incident wave. Besides, chemical doping is applied to turn the Fermi level of graphene and the absorption performance is promoted with the increase of the Fermi level. The experimental results have been demonstrated to have associated resonant peaks with the simulation results. The aim of this paper is to exhibit a systematic study on graphene-based THz metamaterial absorbers, including the simulation and experiments. By comparing the simulation and experimental results, it is useful to clarify the relevant theories and manufacturing processes. The work will provide a further step in the development of high-performance terahertz devices, including tunable absorbers, sensors, and electro-optic switches. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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14 pages, 2793 KiB  
Article
Simulated Performance of a Broadband Solar Absorber Composed of Sectioned Au Disk Structures and ZnS/Au Thin Layers
by Gang Tao, Yingting Yi, Mengxuan Zang, Zhipeng Zheng and Yougen Yi
Coatings 2022, 12(12), 1863; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings12121863 - 30 Nov 2022
Cited by 5 | Viewed by 1173
Abstract
Solar energy is considered an essential source of energy because of cleanliness and ubiquity. However, how to effectively absorb solar energy within the range of solar radiation is an urgent problem to be solved. The design of high-performance broadband perfect absorbers is an [...] Read more.
Solar energy is considered an essential source of energy because of cleanliness and ubiquity. However, how to effectively absorb solar energy within the range of solar radiation is an urgent problem to be solved. The design of high-performance broadband perfect absorbers is an important way to collect solar energy efficiently. In this paper, we propose a novel broadband solar energy absorber based on zinc sulfide (ZnS). It is a three-layer (Au-ZnS-Au) structure with new types of sectioned disks employed in the top layer. The sectioned disks can enhance the absorption efficiency. Surface plasmon polariton (SPP) and electric dipole resonance increase the absorption of light, so the proposed absorber can achieve broadband perfect absorption. Simulation by a finite element analysis (COMSOL) method shows that absorption with a bandwidth of 354 THz from 430 THz–784 THz has been achieved, and the average absorption is 95%. This indicates that the perfect absorption range of the proposed absorber is 78.7% of the visible range. The perfect absorber has four perfect absorption peaks, which can reach a maximum absorption rate of 99.9%. In addition, our absorber is polarization insensitive due to the design of the rotational symmetry structure of the sectioned disks. The absorber is composed of refractory metals so that it can work under actual solar radiation and high-temperature conditions. The proposed solar energy absorber is important for many applications such as solar cells, thermal photovoltaic technology, and sensing. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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13 pages, 3050 KiB  
Article
Design Simulation and Optimization of Germanium-Based Solar Cells with Micro-Nano Cross-Cone Absorption Structure
by Ziyou Zhou, Wenfeng Liu, Yan Guo, Hailong Huang and Xiaolong Ding
Coatings 2022, 12(11), 1653; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings12111653 - 31 Oct 2022
Cited by 7 | Viewed by 1772
Abstract
In this paper, germanium-based solar cells were designed based on germanium (Ge) materials, and the cross-cone (CC) nanostructures were used as the absorber layer of the solar cells. The optical path inside the absorber layer was increased by microstructure reflection, thereby increasing the [...] Read more.
In this paper, germanium-based solar cells were designed based on germanium (Ge) materials, and the cross-cone (CC) nanostructures were used as the absorber layer of the solar cells. The optical path inside the absorber layer was increased by microstructure reflection, thereby increasing the absorption efficiency of the germanium-based solar cell. The reflectivity, transmittance, electric field and magnetic field of the corresponding position of the device were simulated and calculated by the finite difference time domain (FDTD) method. By simulating doping and simulating the external potential difference, the short-circuit current density (JSC), open-circuit voltage (VOC), output power and photoelectric conversion efficiency (η) of the device were calculated. The study found that for the entire study wavelength range (300–1600 nm), the transmittance of the device was close to none, and the average light absorption rate under air mass 1.5 global (AM1.5G) was 94.6%. In the light wavelength range from 310 nm to 1512 nm with a width of 1201 nm, the absorption rate was greater than 90%, which is in line with the high absorption of the broadband. Among them, the absorption rate at 886 nm reached 99.84%, the absorption rate at 1016 nm reached 99.89%, and the absorption rate at 1108 nm reached 99.997%, which is close to full absorption. By exploring the electrical performance of the device under different Ge nanostructure parameters, a germanium-based solar cell device under the nanocross-cone absorption structure array with both high-efficiency light absorption and excellent electrical performance was finally obtained. The study shows that the VOC of its single-junction cell was 0.31 V, JSC reached 45.5 mA/cm2, and it had a fill factor (FF) of 72.7% and can achieve a photoelectric conversion efficiency of 10.3%, surpassing the performance of most Ge solar cells today. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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11 pages, 2721 KiB  
Article
Metamaterial Solar Absorber Based on Refractory Metal Titanium and Its Compound
by Zijun Song, Guolu Ma, Zao Yi, Jianguo Zhang and Yong Zhao
Coatings 2022, 12(7), 929; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings12070929 - 30 Jun 2022
Cited by 4 | Viewed by 1416
Abstract
Metamaterials refers to a class of artificial materials with special properties. Through its unique geometry and the small size of each unit, the material can acquire unique electromagnetic field properties that conventional materials do not have. Based on these factors, we put forward [...] Read more.
Metamaterials refers to a class of artificial materials with special properties. Through its unique geometry and the small size of each unit, the material can acquire unique electromagnetic field properties that conventional materials do not have. Based on these factors, we put forward a kind of high absorption near-ultraviolet to near-infrared electromagnetic wave absorber of the solar energy. The surface structure of the designed absorber is composed of TiN-TiO2-Al2O3 with rectangles and disks, and the substrate is Ti-Al2O3-Ti layer. In the study band range (0.1–3.0 μm), the solar absorber’s average absorption is up to 96.32%, and the designed absorber absorbs more than 90% of the electromagnetic wave with a wavelength width of 2.577 μm (0.413–2.990 μm). Meanwhile, the designed solar absorber has good performance under different angles of oblique incident light. Ultra-wideband solar absorbers have great potential in light absorption related applicaitions because of their wide spectrum high absorption properites. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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7 pages, 1085 KiB  
Article
Optical System Design of a Planar Waveguide Spectrometer
by Shiqun Jin, Zhiming Li, Zhiwei Feng, Lin Gao, Yanduo Li, Long Zhang, Wenjie Shi and Guo Xia
Coatings 2022, 12(4), 520; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings12040520 - 12 Apr 2022
Viewed by 1753
Abstract
In this paper, an optical design for a hollow planar waveguide spectrometer with Czerny-Turner is proposed. To decrease the propagation loss of the spectrometer, the design strategy of designing the tangential plane and the sagittal plane separately is proposed, corresponding to resolution and [...] Read more.
In this paper, an optical design for a hollow planar waveguide spectrometer with Czerny-Turner is proposed. To decrease the propagation loss of the spectrometer, the design strategy of designing the tangential plane and the sagittal plane separately is proposed, corresponding to resolution and energy, respectively. The Czerny–Turner optical path is designed on the tangential plane, and the sagittal design theory and method are analyzed in detail. The ray tracing results show that the resolution of the spectrometer is better than 4 nm on the tangential plane, while on the sagittal plane, the detector receives the highest energy when the detector pixel height matches the distance between the two mirrors. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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7 pages, 4311 KiB  
Article
Spoon-like Beams Generated with Exponential Phases
by Lei Guo, Tian Xia, Yiping Xu, Yan Xiong, Xian Leng, Shaohua Tao, Yonghong Tian and Shubo Cheng
Coatings 2022, 12(3), 322; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings12030322 - 01 Mar 2022
Cited by 2 | Viewed by 1960
Abstract
In this paper, we report a new kind of beam, named “spoon-like” beams, generated with the exponential phase. The intensity distributions and transverse energy flow of the spoon-like beam at the focal plane are analyzed theoretically and experimentally. The results demonstrate that the [...] Read more.
In this paper, we report a new kind of beam, named “spoon-like” beams, generated with the exponential phase. The intensity distributions and transverse energy flow of the spoon-like beam at the focal plane are analyzed theoretically and experimentally. The results demonstrate that the size of the spoon-like beam becomes enlarged with the increasing power exponent n, and the length of the spoon-like intensity trajectory becomes shorter with the increasing parameter p. Furthermore, there is an intensity gradient along the spoon-like trajectory of the beam, which introduces the intensity-gradient force exerted onto microparticles. The experiment on optical tweezers demonstrates that the focused beams can create spoon-like traps for the two-dimensional manipulation of particles. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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13 pages, 5161 KiB  
Article
Towards Investigating Surface Quality of Single-Crystal Silicon Optics Polished with Different Processes
by Laixi Sun, Yubin Zhang, Xiaoyan Zhou, Miaomiao Duan, Xin Ye, Weihua Li, Yaguo Li and Liming Yang
Coatings 2022, 12(2), 158; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings12020158 - 27 Jan 2022
Cited by 4 | Viewed by 2200
Abstract
A series of cleaning and etching experiments utilizing organic solvent or weak alkali solutions were performed on single-crystal silicon optics polished with different processes. Polishing-introduced fractured defects in the subsurface layer were systematically characterized using laser-induced scattering imaging and photothermal weak absorption imaging [...] Read more.
A series of cleaning and etching experiments utilizing organic solvent or weak alkali solutions were performed on single-crystal silicon optics polished with different processes. Polishing-introduced fractured defects in the subsurface layer were systematically characterized using laser-induced scattering imaging and photothermal weak absorption imaging techniques. A white-light interferometer also measured the surface morphology and roughness of the samples to evaluate the surface quality of the optics. The results show that the organic solvent cleaning process can eliminate the surface contamination resulting from the environment and the near-surface polishing-introduced impurities but can not remove the fractured defects in the subsurface layer of the optics. By contrast, weak alkali solution can effectively expose the subsurface defects and decrease the concentration of the embedded absorbing impurities to some extent. The results also imply that the polishing process has a crucial effect on the surface quality (e.g., surface roughness and error) and optical performance (e.g., surface absorption) after the subsequent treatments such as cleaning or etching. The corresponding methodology of cleaning and characterization can serve as a predictive tool for evaluating the polishing level and laser damage resistance of the single-crystal silicon optics. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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13 pages, 6327 KiB  
Article
Ultra-Low-Reflective, Self-Cleaning Surface by Fabrication Dual-Scale Hierarchical Optical Structures on Silicon
by Miaomiao Duan, Jingjun Wu, Yubin Zhang, Ning Zhang, Jun Chen, Zhenhua Lei, Zao Yi and Xin Ye
Coatings 2021, 11(12), 1541; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings11121541 - 15 Dec 2021
Cited by 4 | Viewed by 2224
Abstract
An integrated functional anti-reflective surface is of great significance for optical and optoelectronic devices. Hence, its preparation has attracted great attention from many researchers. This study combined wet alkaline etching approaches and reactive ion etching (RIE) techniques to create a dual-scale hierarchical anti-reflective [...] Read more.
An integrated functional anti-reflective surface is of great significance for optical and optoelectronic devices. Hence, its preparation has attracted great attention from many researchers. This study combined wet alkaline etching approaches and reactive ion etching (RIE) techniques to create a dual-scale hierarchical anti-reflective surface on silicon substrates. The effect of RIE time on surface morphology and optical performance was investigated using multiple characterization forms. The optimal parameters for the fabrication of dual-scale structures by the composite etching process were explored. The silicon surface with a dual-scale structure indicated excellent anti-reflective properties (minimum reflectivity of 0.9%) in the 300 to 1100 nm wavelength range. In addition, the ultra-low reflection characteristic of the surface remained prominent at incident light angles up to 60°. The simulated spectra using the finite difference time domain (FDTD) method agreed with the experimental results. Superhydrophobicity and self-cleaning were also attractive properties of the surface. The functionally integrated surface enables silicon devices to have broad application prospects in solar cells, light emitting diodes (LEDs), photoelectric detectors, and outdoor equipment. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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9 pages, 1476 KiB  
Article
Phase-Change Metasurface by U-Shaped Atoms for Photonic Switch with High Contrast Ratio
by Xiaoyu Ma, Ruirui Song, Zhihua Fan and Shaolin Zhou
Coatings 2021, 11(12), 1499; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings11121499 - 06 Dec 2021
Cited by 4 | Viewed by 2360
Abstract
Currently, diverse metasurfaces act as exotic platforms enabling versatile wave regulations in deep-subwavelength level for ultracompact integration. To address the existing issues of passive nature and low-efficiency in wave controls, one type of metasurface for active phase tuning is proposed in this paper [...] Read more.
Currently, diverse metasurfaces act as exotic platforms enabling versatile wave regulations in deep-subwavelength level for ultracompact integration. To address the existing issues of passive nature and low-efficiency in wave controls, one type of metasurface for active phase tuning is proposed in this paper by integrating the phase-change dielectric of Ge2Sb2Te5 into the of U-shaped meta-atoms. Specifically, the phase-change-based hybrid design of Ge2Sb2Te5-integrated metalens switch is demonstrated and numerically confirmed with switchable focusing. The well-defined metal-insulator-metal (MIM) setup is used to enable high-efficiency reflective wavefront tunig and practical Ge2Sb2Te5 phase transition. Upon the phase transition between the amorphous and crystalline states of Ge2Sb2Te5, the cross-polarized component of reflected waves in the given wavelength range is switched “on” (maximized) for as-designed geometric phase plus meta-lensing or “off” (minimized) for no lensing with ultra-high contrast ratio of ~36:1. As a result, such hybrid design of phase-change metasurface may provide a promising route for active photonic device with compact integration. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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8 pages, 2932 KiB  
Article
Data Analysis of Two-Phase Flow Simulation Experiment of Array Optical Fiber and Array Resistance Probe
by Shuaifei Cui, Junfeng Liu, Kui Li and Qinze Li
Coatings 2021, 11(11), 1420; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings11111420 - 20 Nov 2021
Cited by 4 | Viewed by 1478
Abstract
To solve the problem that traditional single-probe instruments cannot accurately measure the gas and water holdup, the domestic design of the array holdup measuring instrument Array of Optical and Resistance Tool (AORT), composed of five sets of optical fiber probes and five sets [...] Read more.
To solve the problem that traditional single-probe instruments cannot accurately measure the gas and water holdup, the domestic design of the array holdup measuring instrument Array of Optical and Resistance Tool (AORT), composed of five sets of optical fiber probes and five sets of resistance probes, is carried out in both gas–water and oil–water. Simulated measurement experiments were conducted under different water cut in phase flow. Through the analysis of the experimental data, the response relationship between the optical fiber probe and the resistance probe of the AORT instrument in different fluids was obtained. Then, the data under different conditions of fluid, flowrate and water cut in the experiment were compared by drawing. Interpolation algorithm was used to perform two-maintenance holdup imaging, and finally the holdup image was compared with the pictures of the flow in the pipe recorded during the experiment. The results show that the resistance probe has a better response under low water cut conditions, and the optical fiber probe has a better response under high gas cut conditions, which is consistent with the theoretical analysis. The imaging diagram and the flow pattern in the pipe during the experiment are in good agreement. It can be seen that the accuracy of the holdup measured by the AORT instrument under the test conditions is verified, and can provide technical support for further carrying out the measurement and interpretation of the holdup in future, as well as the improvement of the instrument and on-site testing. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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14 pages, 3912 KiB  
Article
Features and Functionality of the Optical Interference Meter for Measurement of Surface Displacements of Control Objects
by Igor P. Miroshnichenko, Ivan A. Parinov, Shun-Hsyung Chang and Chin-Feng Lin
Coatings 2021, 11(8), 989; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings11080989 - 19 Aug 2021
Cited by 2 | Viewed by 1627
Abstract
This article presents in detail the methodology and results of test studies of the functionality of a prospective optical setup for measuring the surface linear displacements of control objects, developed on the basis of a new interference measurement method, namely the “luminous point” [...] Read more.
This article presents in detail the methodology and results of test studies of the functionality of a prospective optical setup for measuring the surface linear displacements of control objects, developed on the basis of a new interference measurement method, namely the “luminous point” method. The dependencies of the changes in intensity of the optical field of interference patterns are obtained, characterizing the features of the functional capabilities of the setup. It is experimentally confirmed that with significant changes in the angle of incidence of radiation on the surface of the control object, the sensitivity of the investigated setup does not change. The noted research results are most appropriate for use in the development of new contactless optical setups for measuring the displacements of the surfaces of control objects, and for use in various experimental works in the processes of the creation and production of machines and equipment, as well as in the diagnosis of the state of structural materials and power elements of machines and equipment during operation. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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13 pages, 3105 KiB  
Article
A Tunable “Ancient Coin”-Type Perfect Absorber with High Refractive Index Sensitivity and Good Angular Polarization Tolerance
by Hao Luo, Qianyi Shangguan, Yinting Yi, Shubo Cheng, Yougen Yi and Zhizhong Li
Coatings 2021, 11(7), 814; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings11070814 - 06 Jul 2021
Cited by 7 | Viewed by 1904
Abstract
In this paper, we design and present a graphene-based “ancient coin”-type dual-band perfect metamaterial absorber, which is composed of a silver layer, silicon dioxide layer, and a top “ancient coin” graphene layer. The absorption performance of the absorber is affected by the hollowed-out [...] Read more.
In this paper, we design and present a graphene-based “ancient coin”-type dual-band perfect metamaterial absorber, which is composed of a silver layer, silicon dioxide layer, and a top “ancient coin” graphene layer. The absorption performance of the absorber is affected by the hollowed-out square in the center of the graphene layer and geometric parameters of the remaining nano disk. The optical properties of graphene can be changed by adjusting the voltage, to control the absorption performance of the absorber dynamically. In addition, the centrally symmetric pattern structure greatly eliminates the polarization angle dependence of our proposed absorber, and it exhibits good angular polarization tolerance. Furthermore, the proposed “ancient coin”-type absorber shows great application potential as a sensor or detector in biopharmaceutical, optical imaging, and other fields due to its strong tunability and high refractive index sensitivity. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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12 pages, 4428 KiB  
Article
Based on Ultrathin PEDOT:PSS/c-Ge Solar Cells Design and Their Photoelectric Performance
by Ju Su, Hua Yang, Yan Xu, Yijun Tang, Zao Yi, Fusheng Zheng, Fei Zhao, Li Liu, Pinghui Wu and Hailiang Li
Coatings 2021, 11(7), 748; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings11070748 - 22 Jun 2021
Cited by 27 | Viewed by 3328
Abstract
In recent years, nanostructures have improved the performance of solar cells and are regarded as the most promising microstructures. The optical properties of PEDOT:PSS/c-Ge hybrid solar cells (HSCs) based on the octagon germanium nanoparticles (O-GNPs) were numerically analyzed using the finite-difference time-domain (FDTD) [...] Read more.
In recent years, nanostructures have improved the performance of solar cells and are regarded as the most promising microstructures. The optical properties of PEDOT:PSS/c-Ge hybrid solar cells (HSCs) based on the octagon germanium nanoparticles (O-GNPs) were numerically analyzed using the finite-difference time-domain (FDTD) method. The optimal structure of the hybrid solar cell is determined by changing the thickness of the organic layer and structural parameters of nanoparticles to enhance the optical absorption and eventually achieve high broadband absorption. By changing the structure parameter of O-GNPs, we studied its effect on solar cells. The optimization of geometric parameters is based on maximum absorption. The light absorption of our optimized HSCs is basically above 90% between 200 and 1500 nm. PEDOT:PSS is placed on top of O-GNPs to transmit the holes better, allowing O-GNPs to capture a lot of photons, to increase absorbance value properties in the AM1.5 solar spectral irradiated region. The transmittance is increased by adding poly-methyl methacrylate (PMMA). At the same time, the electrical characteristics of Ge solar cells were simulated by DEVICE, and short-circuit current (Jsc), open-circuit voltage (Voc), maximum power (Pmax), filling coefficient (FF) and photoelectric conversion efficiency (PCE) were obtained. According to the optimization results after adjusting the structural parameters, the maximum short-circuit current is 44.32 mA/cm2; PCE is 7.84 mW/cm2; FF is 69%. The results show that the O-GNPs have a good light trapping effect, and the structure design has great potential for the absorption of HSCs; it is believed that the conversion efficiency will be further improved through further research. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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8 pages, 5250 KiB  
Article
Reflective Meta-Films with Anti-Damage Property via Field Distribution Manipulation
by Haichao Yu, Feng Tang, Jun Chen, Zao Yi, Xin Ye and Yiqun Wang
Coatings 2021, 11(6), 640; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings11060640 - 27 May 2021
Cited by 2 | Viewed by 2026
Abstract
The reflective optical multi-films with high damage thresholds are widely used in intense-light systems. Metasurfaces, which can manipulate light peculiarly, give a new approach to achieve highly reflective films by a single-layer configuration. In this study, reflective metasurfaces, composed of silicon nanoholes, are [...] Read more.
The reflective optical multi-films with high damage thresholds are widely used in intense-light systems. Metasurfaces, which can manipulate light peculiarly, give a new approach to achieve highly reflective films by a single-layer configuration. In this study, reflective metasurfaces, composed of silicon nanoholes, are numerically investigated to achieve high damage thresholds. These nanoholes can confine the strongest electric field into the air zone, and, subsequently, the in-air electric field does not interact directly with silicon, attenuating the optothermal effect that causes damage. Firstly, the geometrical dependencies of silicon nanoholes’ reflectance and field distribution are investigated. Then, the excitation states of electric/magnetic dipoles in nanostructures are analyzed to explain the electromagnetic mechanism. Furthermore, the reflection dependences of the nanostructures on wavelength and incident angle are investigated. Finally, for a typical reflective meta-film, some optothermal simulations are conducted, in which a maximum laser density of 0.27 W/µm2 can be handled. The study provides an approach to improve the laser damage threshold of reflective nanofilms, which can be exploited in many intense-light applications. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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9 pages, 3211 KiB  
Article
Design of Narrow-Band Absorber Based on Symmetric Silicon Grating and Research on Its Sensing Performance
by Miao Pan, Huazhu Huang, Wenzhi Chen, Shuai Li, Qinglai Xie, Feng Xu, Dongwei Wei, Jun Fang, Baodian Fan and Lihan Cai
Coatings 2021, 11(5), 553; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings11050553 - 08 May 2021
Cited by 5 | Viewed by 2040
Abstract
In this paper, using the surface plasmon and Fabry–Pérot (FP) cavity, the design of a symmetric silicon grating absorber is proposed. The time-domain finite difference method is used for simulation calculations. The basic unit structure is a dielectric grating composed of silicon dioxide, [...] Read more.
In this paper, using the surface plasmon and Fabry–Pérot (FP) cavity, the design of a symmetric silicon grating absorber is proposed. The time-domain finite difference method is used for simulation calculations. The basic unit structure is a dielectric grating composed of silicon dioxide, metal and silicon. Through the adjustment of geometric parameters, we have achieved the best of the symmetric silicon grating absorber. A narrowband absorption peak with an absorption rate greater than 99% is generated in the 3000–5000 nm optical band, and the wavelength of the absorption peak is λ = 3750 nm. The physical absorption mechanism is that silicon light generates surface plasmon waves under the interaction with incident light, and the electromagnetic field coupling of surface plasmon waves and light causes surface plasmon resonance, thereby exciting strong light response modulation. We also explore the influence of geometric parameters and polarization angle on the performance of silicon grating absorbers. Finally, we systematically study the refractive index sensitivity of these structures. These structures can be widely used in optical filtering, spectral sensing, gas detection and other fields. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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9 pages, 15319 KiB  
Article
Experimental Analysis of Gas Holdup Measured by Gas Array Tool in Gas–Water Two Phase of Horizontal Well
by Shuaifei Cui, Junfeng Liu, Xulong Chen and Qinze Li
Coatings 2021, 11(3), 343; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings11030343 - 18 Mar 2021
Cited by 9 | Viewed by 1872
Abstract
In the gas-water two phase of horizontal well, gas holdup is usually obtained by inverse calculation of the water holdup measured by the array capacitance probes. Gas Array Tool (GAT) has been developed to directly measure gas holdup. This instrument has been introduced [...] Read more.
In the gas-water two phase of horizontal well, gas holdup is usually obtained by inverse calculation of the water holdup measured by the array capacitance probes. Gas Array Tool (GAT) has been developed to directly measure gas holdup. This instrument has been introduced into China and its simulation experiment in gas-water two phase flow in horizontal wells has been carried out for the first time to study the applicability of gas holdup measurement. Firstly, the response principle and measurement method of GAT are analyzed; secondly, the experimental data of GAT under different flowrates, water cut, and different cable speed are plotted and analyzed; finally, the gas holdup data measured by GAT and Capacitance Array Tool (CAT) are compared by using an interpolation algorithm. It is found that the response of the optical fiber probe is consistent and stable. It also proves the accuracy of gas identification and the applicability of gas holdup measurement under test conditions by GAT, which lays a foundation for further gas holdup measurement, interpretation, and field test in the future. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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9 pages, 2694 KiB  
Article
Dual-Band Plasmonic Perfect Absorber Based on the Hybrid Halide Perovskite in the Communication Regime
by Liang Xu, Jian Zeng, Xin Luo, Libin Xia, Zongle Ma, Bojun Peng, Zhengquan Li, Xiang Zhai and Lingling Wang
Coatings 2021, 11(1), 67; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings11010067 - 08 Jan 2021
Cited by 14 | Viewed by 1855
Abstract
Due to the weak absorption of (CH3NH3)PbI3 in the communication regime, which restricts its optoelectronic applications, we design a adjustable dual-band perfect absorber based on the (CH3NH3)PbI3 to significantly enhance its absorption capability. [...] Read more.
Due to the weak absorption of (CH3NH3)PbI3 in the communication regime, which restricts its optoelectronic applications, we design a adjustable dual-band perfect absorber based on the (CH3NH3)PbI3 to significantly enhance its absorption capability. Since the localized plasmon (LP) mode and surface plasmon (SP) mode are excited in the structure, which can both greatly enhance light absorption of the (CH3NH3)PbI3 layer, dual-band perfect absorption peaks are formed in the communication regime, and the absorption of (CH3NH3)PbI3 layer is increased to 43.1% and 64.2% at the dual-band absorption peaks by using finite-difference time-domain (FDTD) methods, respectively. By varying some key structural parameters, the dual-band absorption peaks of (CH3NH3)PbI3 can be separately shifted in a wide wavelength region. Moreover, the designed absorber can keep good performance under wide angles of incidence and manifested polarization correlation. Furthermore, not just for (CH3NH3)PbI3, the physical mechanism in this absorber can also be utilized to strengthen the absorption of other halide perovskites. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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7 pages, 10875 KiB  
Article
Incidence Angle Effects on the Fabrication of Microstructures Using Six-Beam Laser Interference Lithography
by Tianxu Jia, Xiangxian Wang, Yaqian Ren, Yingwen Su, Liping Zhang, Hua Yang, Yunping Qi and Weiming Liu
Coatings 2021, 11(1), 62; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings11010062 - 07 Jan 2021
Cited by 10 | Viewed by 2032
Abstract
This paper presents a theoretical demonstration of diverse microstructure fabrication by changing the angle of incidence of a six-beam laser interference lithography system. Different combinations are formed with transverse electric (TE) and transverse magnetic (TM) polarizations and various microstructures are simulated by controlling [...] Read more.
This paper presents a theoretical demonstration of diverse microstructure fabrication by changing the angle of incidence of a six-beam laser interference lithography system. Different combinations are formed with transverse electric (TE) and transverse magnetic (TM) polarizations and various microstructures are simulated by controlling the high-reflectivity mirror group to adjust the incidence angle. This study indicates that the incidence angle has a considerable influence on the shape and period of the lattice, thereby contributing to the fabrication of microstructures with different arrangements. These structures include donut, circle, D-type, rectangular, triangular, U-type, and honeycomb lattices. The six-beam laser interference lithography technique is expected to benefit microstructure fabrication because of its simple operation, large writing area, and low cost, thereby promoting the development of micro-optics. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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11 pages, 4153 KiB  
Article
Temperature Sensing Utilizing Stimulate Brillouin Scattering Fast Light in Liquid-Filled Photonic Crystal Fibers
by Jingli Lei, Shuaibin Niu, Shanglin Hou, Daobin Wang and Xiaoxiao Li
Coatings 2020, 10(11), 1123; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings10111123 - 20 Nov 2020
Cited by 1 | Viewed by 1616
Abstract
A novel temperature sensor designed on stimulate Brillouin scattering fast light in liquid-filled photonic crystal fibers is proposed. The time advancement and the Brillouin frequency shift of fast light are simulated according to the three-wave coupling equations of stimulate Brillouin scattering, and the [...] Read more.
A novel temperature sensor designed on stimulate Brillouin scattering fast light in liquid-filled photonic crystal fibers is proposed. The time advancement and the Brillouin frequency shift of fast light are simulated according to the three-wave coupling equations of stimulate Brillouin scattering, and the temperature sensing characteristics of the fast light in liquid-filled hexagonal photonic crystal fibers with three different air filling factors are simulated from 20 °C to 70 °C by using the full-vector finite element method. The alcohol-filled photonic crystal fibers exhibit rather sensitive responses to temperature. With temperature varying from 20 °C to 70 °C, the variation of the effective mode area is 2.75 µm at the air filling factor of 0.6, the Brillouin frequency shift is about 11 GHz and its average modification is 1.15 MHz. The time advancement increases with the rise of temperature, its increment can reach up to 4.53 ns at the air filling factor of 0.6 and the pump power of 60 mW, the temperature sensitivity of the time advancement is 0.272 ns/°C. Full article
(This article belongs to the Special Issue Micro-Nano Optics and Its Applications)
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