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20 pages, 61915 KiB

Open AccessArticle

Near-Field Vortex Beams Diffraction on Surface Micro-Defects and Diffractive Axicons for Polarization State Recognition

by Dmitry Savelyev and Nikolay Kazanskiy

Sensors 2021, 21(6), 1973; https://0-doi-org.brum.beds.ac.uk/10.3390/s21061973 - 11 Mar 2021

Cited by 22 | Viewed by 3024

The diffraction of vortex Gaussian laser beams by elementary objects of micro-optics (surface micro-defects) to recognize the type of polarization (linear, circular, radial, azimuthal) of the input radiation was investigated in this paper. We considered two main types of defects (protrusion and depression [...] Read more.

The diffraction of vortex Gaussian laser beams by elementary objects of micro-optics (surface micro-defects) to recognize the type of polarization (linear, circular, radial, azimuthal) of the input radiation was investigated in this paper. We considered two main types of defects (protrusion and depression in the form of a circle and a square) with different sizes (the radius and height were varied). Light propagation (3D) through the proposed micro-defects was modeled using the finite difference time domain (FDTD) method. The possibility of recognizing (including size change) of surface micro-defects (protrusions and depressions) and all the above types of polarization are shown. Thus, micro-defects act as sensors for the polarization state of the illuminating beam. The focusing properties of micro-defects are compared with diffractive axicons with different numerical apertures (NAs). The possibility of sub-wavelength focusing with element height change is demonstrated. In particular, it is numerically shown that a silicon cylinder (protrusion) forms a light spot with a minimum size of the all intensity FWHM of 0.28λ. Full article

(This article belongs to the Special Issue Sensors Based on Diffraction Structures)

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19 pages, 4142 KiB

Open AccessCommunication

Small-Sized Interferometer with Fabry–Perot Resonators for Gravitational Wave Detection

by Nikolai Petrov and Vladislav Pustovoit

Sensors 2021, 21(5), 1877; https://0-doi-org.brum.beds.ac.uk/10.3390/s21051877 - 08 Mar 2021

Cited by 8 | Viewed by 1896

Abstract

It is highly desirable to have a compact laser interferometer for detecting gravitational waves. Here, a small-sized tabletop laser interferometer with Fabry–Perot resonators consisting of two spatially distributed “mirrors” for detecting gravitational waves is proposed. It is shown that the spectral resolution of [...] Read more.

It is highly desirable to have a compact laser interferometer for detecting gravitational waves. Here, a small-sized tabletop laser interferometer with Fabry–Perot resonators consisting of two spatially distributed “mirrors” for detecting gravitational waves is proposed. It is shown that the spectral resolution of 10⁻²³ cm⁻¹ can be achieved at a distance between mirrors of only 1–3 m. The influence of light absorption in crystals on the limiting resolution of such resonators is also studied. A higher sensitivity of the interferometer to shorter-wave laser radiation is shown. A method for detecting gravitational waves is proposed based on the measurement of the correlation function of the radiation intensities of non-zero-order resonant modes from the two arms of the Mach–Zehnder interferometer. Full article

(This article belongs to the Special Issue Sensors Based on Diffraction Structures)

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9 pages, 3979 KiB

Open AccessCommunication

Few Percent Efficient Polarization-Sensitive Conversion in Nonlinear Plasmonic Interactions Inside Oligomeric Gold Structures

by Nikolay Busleev, Sergey Kudryashov, Irina Saraeva, Pavel Danilov, Andrey Rudenko, Dmitry Zayarny, Stefan A. Maier, Pham Hong Minh and Andrey Ionin

Sensors 2021, 21(1), 59; https://0-doi-org.brum.beds.ac.uk/10.3390/s21010059 - 24 Dec 2020

Cited by 1 | Viewed by 1914

Abstract

The backscattering spectra of a 500 nm thick gold film, which was excited near the 525 nm transverse localized plasmon resonance of its constituent, self-organized, vertically-aligned nanorods by normally incident 515 nm, 300 fs laser pulses with linear, radial, azimuthal and circular polarizations, [...] Read more.

The backscattering spectra of a 500 nm thick gold film, which was excited near the 525 nm transverse localized plasmon resonance of its constituent, self-organized, vertically-aligned nanorods by normally incident 515 nm, 300 fs laser pulses with linear, radial, azimuthal and circular polarizations, revealed a few-percent conversion into Stokes and anti-Stokes side-band peaks. The investigation of these spectral features based on the nanoscale characterization of the oligomeric structure and numerical simulations of its backscattering response indicated nonlinear Fano-like plasmonic interactions, particularly the partially degenerate four-wave mixing comprised by the visible-range transverse plasmon resonance of the individual nanorods and an IR-range collective mode of the oligomeric structure. Such oligomeric structures in plasmonic films may greatly enhance inner nonlinear electromagnetic interactions and inner near-IR hotspots, paving the way for their engineered IR tunability for broad applications in chemosensing and biosensing. Full article

(This article belongs to the Special Issue Sensors Based on Diffraction Structures)

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15 pages, 4330 KiB

Open AccessArticle

Compact Imaging Systems Based on Annular Harmonic Lenses

by Roman Skidanov, Yury Strelkov, Sergey Volotovsky, Veronika Blank, Sofiya Ganchevskaya, Vladimir Podlipnov, Nikolay Ivliev and Nikolay Kazanskiy

Sensors 2020, 20(14), 3914; https://0-doi-org.brum.beds.ac.uk/10.3390/s20143914 - 14 Jul 2020

Cited by 22 | Viewed by 5941

Abstract

In this study, a configuration of a compact imaging objective based on a reflecting annular harmonic lens was proposed. Light propagation through the proposed optical system was comprehensively modeled using a dedicated special program and the ZEMAX software, with the latter used to [...] Read more.

In this study, a configuration of a compact imaging objective based on a reflecting annular harmonic lens was proposed. Light propagation through the proposed optical system was comprehensively modeled using a dedicated special program and the ZEMAX software, with the latter used to derive the point spread function (PSF). Several relationships were used to describe the connection between key parameters of the objective, including its focal length, field of view, and thickness. We demonstrated that it was possible to design a compact imaging objective whose overall length could be one to two orders of magnitude smaller than its focal length. Using direct laser writing, a reflecting annular harmonic lens was fabricated and used in the proposed objective scheme. The performance of the objective was experimentally studied by imaging a light source and a test pattern. The performance of the compact imaging objective based on a reflecting annular harmonic lens was verified in principle. A PSF value of approximately 16 microns was experimentally obtained, for a lens with a diameter of 25 mm with a focal length of 100 mm. Full article

(This article belongs to the Special Issue Sensors Based on Diffraction Structures)

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18 pages, 9938 KiB

Open AccessEditor’s ChoiceArticle

Wavefront Aberration Sensor Based on a Multichannel Diffractive Optical Element

by Svetlana N. Khonina, Sergey V. Karpeev and Alexey P. Porfirev

Sensors 2020, 20(14), 3850; https://0-doi-org.brum.beds.ac.uk/10.3390/s20143850 - 10 Jul 2020

Cited by 35 | Viewed by 2837

Abstract

We propose a new type of a wavefront aberration sensor, that is, a Zernike matched multichannel diffractive optical filter, which performs consistent filtering of phase distributions corresponding to Zernike polynomials. The sensitivity of the new sensor is theoretically estimated. Based on the theory, [...] Read more.

We propose a new type of a wavefront aberration sensor, that is, a Zernike matched multichannel diffractive optical filter, which performs consistent filtering of phase distributions corresponding to Zernike polynomials. The sensitivity of the new sensor is theoretically estimated. Based on the theory, we develop recommendations for its application. Test wavefronts formed using a spatial light modulator are experimentally investigated. The applicability of the new sensor for the fine-tuning of a laser collimator is assessed. Full article

(This article belongs to the Special Issue Sensors Based on Diffraction Structures)

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13 pages, 4319 KiB

Open AccessArticle

Subwavelength Grating Double Slot Waveguide Racetrack Ring Resonator for Refractive Index Sensing Application

by Nikolay Lvovich Kazanskiy, Svetlana Nikolaevna Khonina and Muhammad Ali Butt

Sensors 2020, 20(12), 3416; https://0-doi-org.brum.beds.ac.uk/10.3390/s20123416 - 17 Jun 2020

Cited by 47 | Viewed by 5239

Abstract

In this paper, a racetrack ring resonator design based on a subwavelength grating double slot waveguide is presented. The proposed waveguide scheme is capable of confining the transverse electric field in the slots and the gaps between the grating segments. This configuration facilitates [...] Read more.

In this paper, a racetrack ring resonator design based on a subwavelength grating double slot waveguide is presented. The proposed waveguide scheme is capable of confining the transverse electric field in the slots and the gaps between the grating segments. This configuration facilitates a large light–matter interaction which elevates the sensitivity of the device approximately 2.5 times higher than the one that can be obtained via a standard slot waveguide resonator. The best sensitivity of the design is obtained at 1000 nm/RIU by utilizing a subwavelength grating double slot waveguide of period 300 nm. The numerical study is conducted via 2D and 3D finite element methods. We believe that the proposed sensor design can play an important role in the realization of highly sensitive lab-on-chip sensors. Full article

(This article belongs to the Special Issue Sensors Based on Diffraction Structures)

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9 pages, 1307 KiB

Open AccessLetter

Lensless Scheme for Measuring Laser Aberrations Based on Computer-Generated Holograms

by George Krasin, Michael Kovalev, Nikita Stsepuro, Pavel Ruchka and Sergey Odinokov

Sensors 2020, 20(15), 4310; https://0-doi-org.brum.beds.ac.uk/10.3390/s20154310 - 02 Aug 2020

Cited by 13 | Viewed by 2765

Abstract

All of the existing holographic wavefront sensors are either bulky or have low accuracy of measuring wavefront aberrations. In this paper, we present an improvement of the holographic method of measuring wavefront aberrations using computer-generated Fourier holograms. The novelty of this work lies [...] Read more.

All of the existing holographic wavefront sensors are either bulky or have low accuracy of measuring wavefront aberrations. In this paper, we present an improvement of the holographic method of measuring wavefront aberrations using computer-generated Fourier holograms. The novelty of this work lies in the proposed approach to the synthesis of Fourier holograms, which are implemented using phase-only SLM. The main advantages of this method are the increased diffraction efficiency compared to the previously known methods, and the more compact implementation scheme due to the elimination of the conventional Fourier-lens. The efficiency of the proposed method was confirmed by numerical simulation and optical experiments. Full article

(This article belongs to the Special Issue Sensors Based on Diffraction Structures)

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10 pages, 2248 KiB

Open AccessLetter

An Airborne Offner Imaging Hyperspectrometer with Radially-Fastened Primary Elements

by Nikolay Kazanskiy, Nikolay Ivliev, Vladimir Podlipnov and Roman Skidanov

Sensors 2020, 20(12), 3411; https://0-doi-org.brum.beds.ac.uk/10.3390/s20123411 - 17 Jun 2020

Cited by 31 | Viewed by 3197

Abstract

We propose a new layout for the Offner imaging hyperspectrometer that is utilized onboard small space vehicles. The layout is based on a method of adjusting the adaptive temperature-dependent optical scheme by moving just two coaxial optical components located inside the hyperspectrometer. We [...] Read more.

We propose a new layout for the Offner imaging hyperspectrometer that is utilized onboard small space vehicles. The layout is based on a method of adjusting the adaptive temperature-dependent optical scheme by moving just two coaxial optical components located inside the hyperspectrometer. We present the results of modeling for a temperature range of −40 to +45 °C and an optical experiment using a heat and cold chamber for the range of 12 to 40 °C, proving the basic functionality of the proposed layout. Based on simulation results, the new layout is supposed to allow the hyperspectrometer to operate in a temperature range of −40 to +45 °C without its optical characteristics deteriorating, thus making it suitable for work onboard space or stratospheric vehicles. Full article

(This article belongs to the Special Issue Sensors Based on Diffraction Structures)

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