Research

16 pages, 59751 KiB

Open AccessArticle

Subwavelength Diffractive Optical Elements for Generation of Terahertz Coherent Beams with Pre-Given Polarization State

by Vladimir Pavelyev, Svetlana Khonina, Sergey Degtyarev, Konstantin Tukmakov, Anton Reshetnikov, Vasily Gerasimov, Natalya Osintseva and Boris Knyazev

Sensors 2023, 23(3), 1579; https://0-doi-org.brum.beds.ac.uk/10.3390/s23031579 - 01 Feb 2023

Cited by 6 | Viewed by 1628

Abstract

Coherent terahertz beams with radial polarization of the 1st, 2nd, and 3rd orders have been generated with the use of silicon subwavelength diffractive optical elements (DOEs). Silicon elements were fabricated by a technology similar to the technology used before for the fabrication of [...] Read more.

Coherent terahertz beams with radial polarization of the 1st, 2nd, and 3rd orders have been generated with the use of silicon subwavelength diffractive optical elements (DOEs). Silicon elements were fabricated by a technology similar to the technology used before for the fabrication of DOEs forming laser terahertz beams with pre-given mode content. The beam of the terahertz Novosibirsk Free Electron Laser was used as the illuminating beam. The experimental results are in good agreement with the results of the computer simulation. Full article

(This article belongs to the Special Issue UV, Infrared and THz Radiation Sensing System)

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19 pages, 14444 KiB

Open AccessArticle

A Numerical Investigation of Graphene-Based Hilbert-Shaped Multi-Band MIMO Antenna for the Terahertz Spectrum Applications

by Khaled Aliqab, Meshari Alsharari, Vishal Sorathiya and Ammar Armghan

Sensors 2023, 23(1), 37; https://0-doi-org.brum.beds.ac.uk/10.3390/s23010037 - 20 Dec 2022

Cited by 4 | Viewed by 1615

Abstract

We proposed the numerical investigation of Hilbert-shaped multiple-input multi-output (MIMO) with multi-band operation characteristics using graphene resonator material, which operates on the band of 1 to 30 THz of the frequency range. This numerical investigation of antenna structure was carried out for the [...] Read more.

We proposed the numerical investigation of Hilbert-shaped multiple-input multi-output (MIMO) with multi-band operation characteristics using graphene resonator material, which operates on the band of 1 to 30 THz of the frequency range. This numerical investigation of antenna structure was carried out for the multiple antenna types, consisting of graphene as a regular patch, Hilbert order 1, and Hilbert order 2 designs. This antenna is investigated for the multiple physical parameters, such as return loss, gain, bandwidth, radiation response, Envelope Correlation Coefficient (ECC), Total Active Reflection Coefficient (TARC), Mean Effective Gain (MEG), Directivity Gain (DG), and Channel Capacity Loss (CCL). These variables are also determined to verify compatibility and the difficulties connected with communicating over a short distance. The THz MIMO antenna that was recommended offers strong isolation values in addition to an operational band. The maximum gain of ~10 dBi for the band of <15 THz and ~17 dBi for the band of the >15 THz frequency range of the proposed antenna structures. The proposed antennas are primarily operated in three bands over 1 to 30 THz of frequency. This work aims to create a brand new terahertz antenna structure capable of providing an extraordinarily wider bandwidth and high gain while keeping a typical compact antenna size suited for terahertz applications. Full article

(This article belongs to the Special Issue UV, Infrared and THz Radiation Sensing System)

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9 pages, 3128 KiB

Open AccessArticle

A New Approach for Sensitive Characterization of Semiconductor Laser Beams Using Metal-Semiconductor Thermocouples

by Anna Katarzyna Piotrowska, Adam Łaszcz, Michał Zaborowski, Artur Broda and Dariusz Szmigiel

Sensors 2022, 22(23), 9324; https://0-doi-org.brum.beds.ac.uk/10.3390/s22239324 - 30 Nov 2022

Viewed by 1296

Abstract

This paper presents the results of beam investigations on semiconductor IR lasers using novel detectors based on thermocouples. The work covers the design, the fabrication of detectors, and the experimental validation of their sensitivity to IR radiation. The principle of operation of the [...] Read more.

This paper presents the results of beam investigations on semiconductor IR lasers using novel detectors based on thermocouples. The work covers the design, the fabrication of detectors, and the experimental validation of their sensitivity to IR radiation. The principle of operation of the manufactured detectors is based on the Seebeck effect (the temperature difference between hot and cold junctions induced voltage appearance). The devices were composed of several thermocouples arranged in a linear array. The nano- and microscale thermocouples (the hot junctions) were fabricated using a typical Si-compatible MEMS process enhanced with focused ion beam (FIB) milling. The performance of the hot junctions was tested, focusing on their sensitivity to IR radiation covering the near-infrared (NIR) radiation (λ = 976 nm). The output voltage was measured as a function of the detector position in the XY plane. The measurement results allowed for reconstructing the Gaussian-like intensity distribution of the incident light beam. Full article

(This article belongs to the Special Issue UV, Infrared and THz Radiation Sensing System)

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17 pages, 7490 KiB

Open AccessArticle

Responsivity and NEP Improvement of Terahertz Microbolometer by High-Impedance Antenna

by Arie Pangesti Aji, Hiroaki Satoh, Catur Apriono, Eko Tjipto Rahardjo and Hiroshi Inokawa

Sensors 2022, 22(14), 5107; https://0-doi-org.brum.beds.ac.uk/10.3390/s22145107 - 07 Jul 2022

Cited by 3 | Viewed by 1732

Abstract

The antenna-coupled microbolometer with suspended titanium heater and thermistor was attractive as a terahertz (THz) detector due to its structural simplicity and low noise levels. In this study, we attempted to improve the responsivity and noise-equivalent power (NEP) of the THz detector by [...] Read more.

The antenna-coupled microbolometer with suspended titanium heater and thermistor was attractive as a terahertz (THz) detector due to its structural simplicity and low noise levels. In this study, we attempted to improve the responsivity and noise-equivalent power (NEP) of the THz detector by using high-resistance heater stacked on the meander thermistor. A wide range of heater resistances were prepared by changing the heater width and thickness. It was revealed that the electrical responsivity and NEP could be improved by increasing the heater’s resistance. To make the best use of this improvement, a high-impedance folded dipole antenna was introduced, and the optical performance at 1 THz was found to be better than that of the conventional halfwave dipole antenna combined with a low-resistance heater. Both the electrical and optical measurement results indicated that the increase in heater resistance could reduce the thermal conductance in the detector, thus improved the responsivity and NEP even if the thermistor resistance was kept the same. Full article

(This article belongs to the Special Issue UV, Infrared and THz Radiation Sensing System)

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16 pages, 8027 KiB

Open AccessArticle

Device for Identifying the UV Emission Spectrum

by Robert Jenő Kovács, Jenő-Zoltán Kovács and Lorant Andras Szolga

Sensors 2022, 22(13), 4852; https://0-doi-org.brum.beds.ac.uk/10.3390/s22134852 - 27 Jun 2022

Cited by 2 | Viewed by 2217

Abstract

Nowadays, the disinfection of classrooms, shopping malls, and offices has become an important part of our lives. One of the most effective disinfection methods is ultraviolet (UV) radiation. To ensure the disinfection device has the required wavelength spectrum, we need to measure it [...] Read more.

Nowadays, the disinfection of classrooms, shopping malls, and offices has become an important part of our lives. One of the most effective disinfection methods is ultraviolet (UV) radiation. To ensure the disinfection device has the required wavelength spectrum, we need to measure it with dedicated equipment. Thus, in this work, we present the development of a UV spectrum detector capable of identifying UV wavelength spectrums, with a wide range of probes and the ability to transmit data to a PC for later evaluation of the results. The device was developed with four UV sensors: one for UV-A, one for UV-B, one for UV-C, and one with a wide range of detection of UVA, with a built-in transimpedance amplifier. An Arduino Nano development board processes all the acquired data. We developed a custom light source containing seven UV LEDs with different central wavelengths to calibrate the device. For easy visualization of the results, custom PC software was developed in the Processing programming medium. For the two pieces of electronics—the UV detector and calibration device—3D-printed housings were created to be ergonomic for the end-user. From the price point of view, this device is affordable compared to what we can find on the market. Full article

(This article belongs to the Special Issue UV, Infrared and THz Radiation Sensing System)

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17 pages, 12840 KiB

Open AccessArticle

Free-Space Transmission and Detection of Variously Polarized Near-IR Beams Using Standard Communication Systems with Embedded Singular Phase Structures

by Sergey V. Karpeev, Vladimir V. Podlipnov, Svetlana N. Khonina, Nikolay A. Ivliev and Sofia V. Ganchevskay

Sensors 2022, 22(3), 890; https://0-doi-org.brum.beds.ac.uk/10.3390/s22030890 - 24 Jan 2022

Cited by 3 | Viewed by 2154

Abstract

We propose to achieve multichannel information transmission in free space by means of variously polarized beams. The interaction of vortex beams of various orders with the main polarization states is theoretically analyzed. The passage of beams with different polarization states through multi-order diffractive [...] Read more.

We propose to achieve multichannel information transmission in free space by means of variously polarized beams. The interaction of vortex beams of various orders with the main polarization states is theoretically analyzed. The passage of beams with different polarization states through multi-order diffractive optical elements (DOEs) is simulated numerically. Using the simulation results, tables of code correspondence of diffraction order numbers to the presence of phase vortices in the analyzed beams are constructed, which allow one to determine diffraction orders that carry information about various polarization states. The performed experiment made it possible to study the recognition of the first order cylindrical polarization state formed by a Q-plate converter using a phase DOE. In the experiment, these elements were built into a commercial fiber-optic communication system operating at the near-IR frequencies. After detecting the beam polarization state, beams of the required diffraction orders are efficiently coupled into optical fiber using an additional phase element. The developed optical detection system also provides channel suppression of homogeneously polarized components, which are supposed to be used for transmission of other channels. Full article

(This article belongs to the Special Issue UV, Infrared and THz Radiation Sensing System)

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13 pages, 7256 KiB

Open AccessArticle

Laser Ablated Nanocrystalline Diamond Membrane for Infrared Applications

by Maxim S. Komlenok, Margarita A. Dezhkina, Vadim S. Sedov, Oleg A. Klimenko, Sergey A. Dyakov and Nikolay A. Gippius

Sensors 2022, 22(3), 829; https://0-doi-org.brum.beds.ac.uk/10.3390/s22030829 - 22 Jan 2022

Cited by 4 | Viewed by 1605

Abstract

We are reporting on laser microstructuring of thin nanocrystalline diamond membranes, for the first time. To demonstrate the possibility of microstructuring, we fabricated a diamond membrane, of 9

μ

m thickness, with a two-dimensional periodic array of closely located chiral elements. We describe [...] Read more.

We are reporting on laser microstructuring of thin nanocrystalline diamond membranes, for the first time. To demonstrate the possibility of microstructuring, we fabricated a diamond membrane, of 9

μ

m thickness, with a two-dimensional periodic array of closely located chiral elements. We describe the fabrication technique and present the results of the measurements of the infrared transmission spectra of the fabricated membrane. We theoretically studied the reflection, transmission, and absorption spectra of a model structure that approximates the fabricated chiral metamembrane. We show that the metamembrane supports quasiguided modes, which appear in the optical spectra due to grating-assisted diffraction of the guided modes to the far field. Due to the C

_{4}

symmetry, the structure demonstrates circular dichroism in transmission. The developed technique can find applications in infrared photonics since diamond is transparent at wavelengths >6

μ

m and has record values of hardness. It paves the way for creation of new-generation infrared filters for circular polarization. Full article

(This article belongs to the Special Issue UV, Infrared and THz Radiation Sensing System)

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10 pages, 3100 KiB

Open AccessArticle

Numerical Optimization of Refractive Index Sensors Based on Diffraction Gratings with High Aspect Ratio in Terahertz Range

by Oleg Kameshkov, Vasily Gerasimov and Boris Knyazev

Sensors 2022, 22(1), 172; https://0-doi-org.brum.beds.ac.uk/10.3390/s22010172 - 28 Dec 2021

Cited by 7 | Viewed by 1905

Abstract

Terahertz surface plasmon resonance (SPR) sensors have been regarded as a promising technology in biomedicine due to their real-time, label-free, and ultrasensitive monitoring features. Different authors have suggested a lot of SPR sensors, including those based on 2D and 3D metamaterials, subwavelength gratings, [...] Read more.

Terahertz surface plasmon resonance (SPR) sensors have been regarded as a promising technology in biomedicine due to their real-time, label-free, and ultrasensitive monitoring features. Different authors have suggested a lot of SPR sensors, including those based on 2D and 3D metamaterials, subwavelength gratings, graphene, and graphene nanotube, as well as others. However, one of the traditional approaches to realize high sensitivity SPR sensors based on metal diffraction gratings has been studied poorly in the terahertz frequency range. In this article, a linear metal rectangular diffraction grating with high aspect ratio is studied. The influence of the grating structure parameters on the sensor sensitivity is simulated. Effects arising from different ratios of depth and width were discovered and explained. The results show that the sensitivity can be increased to 2.26 THz/RIU when the refractive index range of the gas to measure is between 1 and 1.002 with the resolution

5 \times 10^{- 5} RIU

. Full article

(This article belongs to the Special Issue UV, Infrared and THz Radiation Sensing System)

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