Research

11 pages, 2947 KiB

Open AccessArticle

Spontaneous Emission Studies for Blue and Green InGaN-Based Light-Emitting Diodes and Laser Diodes

by Dae-Choul Choi, Yoon Seok Kim, Kyoung-Bo Kim and Sung-Nam Lee

Photonics 2024, 11(2), 135; https://0-doi-org.brum.beds.ac.uk/10.3390/photonics11020135 - 31 Jan 2024

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We investigated the efficiency droop phenomenon in blue and green GaN-based light-emitting diodes (LEDs) and laser diodes (LDs), which poses a significant challenge in high-power LEDs and is characterized by a reduction in external quantum efficiency at higher injection currents. Utilizing identical epi-structures [...] Read more.

We investigated the efficiency droop phenomenon in blue and green GaN-based light-emitting diodes (LEDs) and laser diodes (LDs), which poses a significant challenge in high-power LEDs and is characterized by a reduction in external quantum efficiency at higher injection currents. Utilizing identical epi-structures for blue and green LEDs and LDs, with variations only in indium composition, our experiments revealed a gradual blue shift in the emission wavelengths as the injection current increased. Notably, the blue LED demonstrated a smaller shift compared to the green LED. In addition, the full width at half maximum of emission spectra increased with increasing injection current density, indicative of efficiency droop. Significantly, LDs consistently exhibited lower junction temperatures despite operating at higher current densities. This is attributed to the enhanced heat dissipation capability of the ridge waveguide LD structure, which results in a narrower emission spectrum and reduced efficiency droop compared to mesa LED structures. These outcomes highlight the efficiency of the ridge waveguide LD structure in heat dissipation from the active layer, offering crucial insights for the advancement of high-power light-emitting devices. Full article

(This article belongs to the Special Issue Photodetector Materials and Optoelectronic Devices)

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9 pages, 1110 KiB

Open AccessArticle

A Novel Eye Hole Method for the Crosstalk Test of Small Element Infrared Focal Plane Arrays

by Zhijin Hou, Yan Chen, Jianlu Wang and Junhao Chu

Photonics 2024, 11(1), 77; https://0-doi-org.brum.beds.ac.uk/10.3390/photonics11010077 - 15 Jan 2024

Viewed by 751

Abstract

The crosstalk of the small detection photosensitive elements test has always been the difficulty of research on infrared focal plane arrays (IRFPAs). With the decrease in the element size in the IRFPAs, the crosstalk of small detection photosensitive elements cannot be tested by [...] Read more.

The crosstalk of the small detection photosensitive elements test has always been the difficulty of research on infrared focal plane arrays (IRFPAs). With the decrease in the element size in the IRFPAs, the crosstalk of small detection photosensitive elements cannot be tested by the existing small spot method. In this paper, a novel eye hole method to realize the crosstalk of the small element IRFPAs test is proposed. The novel eye hole method is to make eye holes on the substrate. The transmittance of the eye holes in the substrate is 100%, while the transmittance of the other component in the substrate is 0. The substrate with the eye holes is fixed in front of small element IRFPAs to achieve the crosstalk of the small elements test. The filters selected by 9 elements and 25 elements as the eye hole unit are designed and prepared. The experimental results show that 25 elements are selected as the eye hole unit for the IRFPAs with the element size of 25 μm × 25 μm. The eye holes are formed tightly and repeatedly arranged. The crosstalk of the InSb IRFPAs with the element size of 25 μm × 25 μm by the novel eye hole method is 3.86%. The results are of great reference significance for improving the test level of small element IRFPA. Full article

(This article belongs to the Special Issue Photodetector Materials and Optoelectronic Devices)

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11 pages, 2416 KiB

Open AccessArticle

Solution-Processed Functionalized MoS₂ Nanosheets Composite for Photodetection Application

by Alexander V. Kukhta, Enliu Hong, Nadzeya I. Valynets, Sergei A. Maksimenko, Uladzislau Parkhomenka, Nikita Belko, Anatoly Lugovsky, Tatiana A. Pavich, Iryna N. Kukhta, Ziqing Li and Xiaosheng Fang

Photonics 2023, 10(12), 1295; https://0-doi-org.brum.beds.ac.uk/10.3390/photonics10121295 - 24 Nov 2023

Viewed by 845

Abstract

Charge-transfer organic-inorganic complexes have demonstrated great potential in optoelectronic applications. Herein, a drop-casting processed photodetector based on thick composite films made of multi-layered MoS₂ nanosheets chemically bonded to linear molecules of aromatic thiols has been developed. Composites based on multilayered nanosheets allow [...] Read more.

Charge-transfer organic-inorganic complexes have demonstrated great potential in optoelectronic applications. Herein, a drop-casting processed photodetector based on thick composite films made of multi-layered MoS₂ nanosheets chemically bonded to linear molecules of aromatic thiols has been developed. Composites based on multilayered nanosheets allow for facile preparation of low-cost, large-area, and flexible devices. It was demonstrated that a simple functionalization of ultradispersed MoS₂ nanosheets with linear aromatic thiol results in the formation of charge and energy transfer complexes. A photodetector with functionalized MoS₂ nanosheet film prepared by drop coating with Au electrodes demonstrated enhanced performance compared to pure materials. Our first experiments illustrated that functionalization of MoS₂ nanosheets by a paraquaterphenyl thiol derivative leads to a significant increase in the photoresponse speed (by a factor of 12) and decay speed (by a factor of 17.5), in addition to the enhancement of the photostability of the MoS₂ based photodetector. The photo current value has been increased by about an order of magnitude. The proposed approach offers promising prospects for further development of photodetectors. Full article

(This article belongs to the Special Issue Photodetector Materials and Optoelectronic Devices)

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12 pages, 10570 KiB

Open AccessArticle

Parallel Phase-Shifting Digital Holographic Phase Imaging of Micro-Optical Elements with a Polarization Camera

by Bingcai Liu, Xinmeng Fang, Ailing Tian, Siqi Wang, Ruixuan Zhang, Hongjun Wang and Xueliang Zhu

Photonics 2023, 10(12), 1291; https://0-doi-org.brum.beds.ac.uk/10.3390/photonics10121291 - 23 Nov 2023

Cited by 1 | Viewed by 845

Abstract

In this paper, we propose a measurement method of micro-optical elements with parallel phase-shifting digital holographic phase imaging. This method can record four phase-shifting holograms with a phase difference of π/2 in a single shot and correct the pixel mismatch error of the [...] Read more.

In this paper, we propose a measurement method of micro-optical elements with parallel phase-shifting digital holographic phase imaging. This method can record four phase-shifting holograms with a phase difference of π/2 in a single shot and correct the pixel mismatch error of the polarization camera using a bilinear interpolation algorithm, thereby producing high-resolution four-step phase-shifting holograms. This method reconstructs the real phase information of the object to be measured through a four-step phase-shifting algorithm. The reproduced image eliminates the interference of zero-order images and conjugate images, overcoming the problem that traditional phase-shifting digital holography cannot be measured in real time. A simulation analysis showed that the relative error of this measurement method could reach 0.0051%. The accurate surface topography information of the object was reconstructed from an experimental measurement through a microlens array. Multiple measurements yielded a mean absolute error and a mean relative error for the vertical height of the microlens array down to 5.9500 nm and 0.0461%, respectively. Full article

(This article belongs to the Special Issue Photodetector Materials and Optoelectronic Devices)

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13 pages, 6788 KiB

Open AccessArticle

Preparation and Performance Study of Photoconductive Detector Based on Bi₂O₂Se Film

by Jun Liu, Zhonghui Han, Jianning Ding, Kang Guo, Xiaobin Yang, Peng Hu, Yang Jiao and Feng Teng

Photonics 2023, 10(11), 1187; https://0-doi-org.brum.beds.ac.uk/10.3390/photonics10111187 - 25 Oct 2023

Cited by 1 | Viewed by 953

Abstract

Bi₂O₂Se, as a novel two-dimensional semiconductor material, has been prepared and used in the field of photodetection. Herein, Bi₂O₂Se nanosheets were prepared using a hydrothermal method. Bi₂O₂Se films were also prepared [...] Read more.

Bi₂O₂Se, as a novel two-dimensional semiconductor material, has been prepared and used in the field of photodetection. Herein, Bi₂O₂Se nanosheets were prepared using a hydrothermal method. Bi₂O₂Se films were also prepared using a drop-coating method. A photoconductive detector based on the Bi₂O₂Se film was constructed. The influence of nanosheet size was considered. Ultrasonic crashing treatments and different drying processes were used for the improvement of device performance. The obtained results demonstrate that the Bi₂O₂Se film based on treated nanosheets is denser and more continuous, leading to a higher photocurrent (1.4 nA). Drying in a vacuum can further increase the photocurrent of the device (3.0 nA). The photocurrent would increase with the increase in drying temperatures, while the dark current increases synchronously, leading to a decrease in the on/off ratio. The device based on Bi₂O₂Se film was dried in a vacuum at 180 °C and exhibited high responsivity (28 mA/W) and detectivity (~4 × 10⁹ Jones) under 780 nm light illumination. Together, these results provide a data foundation and vision for the further development of photodetectors based on Bi₂O₂Se material. Full article

(This article belongs to the Special Issue Photodetector Materials and Optoelectronic Devices)

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14 pages, 4310 KiB

Open AccessArticle

Investigating the Role of Temperature in Laser Assisted Chemical Bath Deposition for ZnO Growth for Photodetector Application

by Naser M. Ahmed, Loh Xue Qi, Anoud Saud Alshammari, Amel Muhson Naji, Humberto Cabrera, Ayed M. Binzowaimil, Osamah A. Aldaghri and Khalid H. Ibnaouf

Photonics 2023, 10(8), 910; https://0-doi-org.brum.beds.ac.uk/10.3390/photonics10080910 - 07 Aug 2023

Cited by 3 | Viewed by 851

Abstract

ZnO microrods (ZnO-MRs) have unique properties that make them highly attractive for applications such as optoelectronics, electronics, and sensors. This work demonstrates the successful synthesis of high-quality ZnO-MRs using a laser-assisted chemical bath deposition method. The optimal growth temperature for high-quality ZnO-MRs was [...] Read more.

ZnO microrods (ZnO-MRs) have unique properties that make them highly attractive for applications such as optoelectronics, electronics, and sensors. This work demonstrates the successful synthesis of high-quality ZnO-MRs using a laser-assisted chemical bath deposition method. The optimal growth temperature for high-quality ZnO-MRs was found to be 61.10 °C, considerably lower than that required for conventional chemical methods. Various characterization techniques, including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy Dispersive X-ray (EDX), and UV-Vis spectrometry, confirmed the structural and optical properties of the synthesized ZnO-MRs. The UV detection potentialities of the fabricated ZnO-MRs were investigated. All samples exhibited good UV detection capabilities with the sample grown at 61.10 °C showing the best performance with fast response and recovery times of 1.260 s and 1.398 s, respectively. These findings hold immense potential for developing more efficient methods for synthesizing ZnO-MRs for use in various applications. Full article

(This article belongs to the Special Issue Photodetector Materials and Optoelectronic Devices)

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15 pages, 19457 KiB

Open AccessArticle

Non-Contact Global Measurement of the Engine in Working Condition

by Guoce Hu, Jun Wang, Huaxia Deng, Mengchao Ma and Xiang Zhong

Photonics 2023, 10(7), 801; https://0-doi-org.brum.beds.ac.uk/10.3390/photonics10070801 - 10 Jul 2023

Viewed by 697

Abstract

Vibration measurements are essential for studying the dynamic properties of structures, as they can better capture the global characteristics of the structure. This paper proposes a three-dimensional measurement method based on projected structured light to address the challenge of measuring the vibration information [...] Read more.

Vibration measurements are essential for studying the dynamic properties of structures, as they can better capture the global characteristics of the structure. This paper proposes a three-dimensional measurement method based on projected structured light to address the challenge of measuring the vibration information of engine pipes during operation. By using the data obtained from this method and applying the time domain analysis method for modal analysis, the modal parameters of the engine under operating conditions can be obtained. The feasibility of this method is demonstrated by comparing it with different measurement methods, and it provides an effective solution for modal identification of engines under operating conditions. Full article

(This article belongs to the Special Issue Photodetector Materials and Optoelectronic Devices)

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9 pages, 3955 KiB

Open AccessCommunication

Angle-Selective Photodetection in Ge/Si Quantum Dot Photodiodes Enhanced by Microstructured Hole Arrays

by Andrew I. Yakimov, Victor V. Kirienko, Aleksei A. Bloshkin, Dmitrii E. Utkin and Anatoly V. Dvurechenskii

Photonics 2023, 10(7), 764; https://0-doi-org.brum.beds.ac.uk/10.3390/photonics10070764 - 02 Jul 2023

Viewed by 976

Abstract

We report on the near-infrared (NIR) photoresponse of a micropatterned Ge/Si quantum dot (QD) pin photodiode at different angles of radiation incidence. The photon-trapping hole array was etched through the n+-type top contact layer to reach the buried QDs. The normal-incidence responsivity was [...] Read more.

We report on the near-infrared (NIR) photoresponse of a micropatterned Ge/Si quantum dot (QD) pin photodiode at different angles of radiation incidence. The photon-trapping hole array was etched through the n+-type top contact layer to reach the buried QDs. The normal-incidence responsivity was observed to be resonantly increased at wavelengths of 1.4, 1.7, and 1.9

μ

m by factors of 40, 33, and 30, respectively, compared with the reference detector without holes. As the incident angle

θ

increases, the resonance peaks are disappeared and at

θ > 40^{\circ}

a new resonance with a

25 \times

enhancement arises at a wavelength of 1.8

μ

m. Simulation of the near-field intensity, Poynting vector distribution and wave polarization showed that at small

θ

, the strong electric field is primarily localized under the air holes (1.4

μ

m, TM mode) or between the holes (1.7 and 1.9

μ

m, TE modes) inside the region occupied by QDs, resulting in the strong NIR photocurrent. At large

θ

, the dominant resonance detected at 1.8

μ

m is the result of coupling between the TE and TM modes and formation of a mixed near-field state. Full article

(This article belongs to the Special Issue Photodetector Materials and Optoelectronic Devices)

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