Polarization Sensitivity Research Articles

Polarization-Sensitive Self-Powered Schottky Photodetector with High Photovoltaic Performance Induced by Geometry-Asymmetric Contacts.

Polarization-sensitive photodetectors have attracted considerable attention owing to their potential application prospects in navigation, optical switching, and communication. However, it remains challenging to develop a facile and effective strategy to simultaneously meet the demands of low power consumption, high performance, and excellent polarization sensitivity. Herein, a series of low-symmetry two-dimensional (2D) ReSe2 Schottky photodetectors with geometry-asymmetric contacts are constructed. These devices exhibit excellent photoelectrical performance and impressive polarization sensitivity in the self-powered mode owing to the difference in the Schottky barrier height induced by the asymmetric contact areas, interfacial states, and thickness difference. Particularly, an outstanding responsivity of 379 mA/W, a decent specific detectivity of 6.8 × 1011 Jones, and a high light on/off ratio (Ilight/Idark) of over 105 under 635 nm light illumination are achieved. Scanning photocurrent mapping (SPCM) measurements further confirm that the ReSe2/drain overlapped region (corresponding to the smaller contact area side) with a higher Schottky barrier height plays a dominant role in the generation of photocurrent. Furthermore, the proposed device displays impressive polarization ratios (PRs) of 3.1 and 3.6 at zero bias under 635 and 808 nm irradiation, respectively. The high-resolution single-pixel imaging capability is also demonstrated. This work reveals the great potential of the ReSe2 Schottky photodetector with geometry-asymmetric contacts for high-performance, self-powered, and polarization-sensitive photodetection.

High-performance absorber with substitutable materials for short-wave infrared sensing

The optical absorption device plays a crucial role as a component of the infrared astronomical telescope and possesses a significant impact on astronomical observations. A simple metamaterial absorber with substitutable middle materials is made for short-wave infrared sensing. The absorber is designed as a hollow square column, using a patterning approach for the top-layer structure of metamaterials. The absorption characteristics are verified using the impedance matching method, which involves extracting S-parameters and then performing inverse calculations to determine the absorber’s equivalent impedance. The result shows the highest absorption peak is at 3.25 μm, reaching 99.71%, with an impressive average absorption rate of 99.01% between 1.52 and 3.66 μm. The results demonstrate that this absorber shows polarization insensitivity while maintaining high absorption even at large angles of incidence. The distribution of the electromagnetic field within the absorber, the electromagnetic losses within individual layers, and their impact on the absorptive performance are analyzed in detail. Polarization angles, transverse magnetic polarization, and transverse electric polarization are further explored. The parameters of each layer have been discussed. An investigation of the intermediate dielectric layer has been conducted. The proposed absorber shows the potential to achieve exceptional absorption performance under various dielectric conditions, rendering it a promising candidate for use in astronomical observation, medical tests, infrared detection, invisible short-wave infrared systems, radar and various optical devices.

Design and Modeling of a Miniaturized Multilayer Metamaterial Absorber With Oblique Angle and Polarization Insensitivity

Design and Modeling of a Miniaturized Multilayer Metamaterial Absorber With Oblique Angle and Polarization Insensitivity

Study of surface plasmon resonance with zirconium oxide multilayer coatings of silver and gold films: reflection polarization modes and sensitivity

We propose a surface plasmon resonance (SPR) sensor based on multilayer films with silver (Ag) and gold (Au) interfaces coated with a thin layer of zirconium oxide (ZrO2) in Kretschmann configuration. A dielectric layer of ZrO2 acts as the prism coating and the second layer is deposited after the metal film in the dielectric/metal/dielectric (DMD) system. In order to achieve the best design for the sensor, the dependence of the sensitivity on the angle of incidence and the thickness of the alternating layer is comprehensively explored. The polarization change results are shown with the angles Ψ and ∆ which are the traditional ellipsometry measurement angles of the optical properties of the DMD system. The advantage of Ag/ZrO2 multilayers over Au and Au/ZrO2 for SPR refractive index detection in terms of sensitivity, as well as the Ag/ZrO2 interface offers the possibility of studies with promising features for SPR users to generalize this type of interface. The proposed DMD sensor is expected to find application in biochemical sensing due to its resolution.

Multispectral MoSi superconducting nanowire single photon detector

In this paper, a multispectral superconducting nanowire single photon detector (SNSPD) with high absorption efficiency is designed. It consists of Ag reflector, two SiO layers, Si slot and MoSi nanowire. Considering two typical quantum communication wavelengths (1310 nm and 1550 nm), when filling factor is 30 %, numerical simulation results show that the absorption efficiency of SNSPD can be over 95 % at each wavelength separately, and over 86 % at two target wavelengths simultaneously after introducing the second SiO layer and adjusting the structure parameters. And when filling factor is set to 40 %, the results at two target wavelengths are over 93 % and a broadband absorption (>80 %) of 1140 nm–1600 nm appears. In addition, the polarization sensitivity of the two-SiO-layers SNSPD is analyzed. When filling factor is over 63 %, the SNSPD attains both high absorption efficiency and TM-TE polarization insensitivity at two target wavelengths. The results of this work may provide access to fabricate high-efficiency and multispectral SNSPDs, and find applications in quantum optics and quantum communication systems.

Highly Sensitive Broadband Polarized Photodetector Based on the As0.6P0.4/WSe2 Heterostructure toward Imaging and Optical Communication Application.

Polarization-sensitive photodetectors based on two-dimensional anisotropic materials still encounter the issues of narrow spectral coverage and low polarization sensitivity. To address these obstacles, anisotropic As0.6P0.4 with a narrow band gap has been integrated with WSe2 to construct a type-II heterostructure, realizing a high-performance polarization-sensitive photodetector with broad spectral range from 405 to 2200 nm. By operating in photovoltaic mode at zero bias, the device shows a very low dark current of ∼0.02 picoampere, high responsivity of 492 m A/W, and high photoswitching ratio of 6 × 104, yielding a high specific detectivity of 1.4 × 1012 Jones. The strong in-plane anisotropy of As0.6P0.4 endows the device with a capability of polarization-sensitive detection with a high polarization ratio of 6.85 under a bias voltage. As an image sensor and signal receiver, the device shows great potential in imaging and optical communication applications. This work develops an anisotropic vdW heterojunction to realize polarization-sensitive photodetectors with wide spectral coverage, fast response, and high sensitivity, providing a new candidate for potential applications of polarization-resolved electronics and photonics.

High-performance eight-channel system with fractal superconducting nanowire single-photon detectors

Superconducting nanowire single-photon detectors (SNSPDs) have become a mainstream photon-counting technology that has been used in various applications. So far, most multi-channel SNSPD systems, either reported in literature or been commercially available, are polarization sensitive, that is, the system detection efficiency (SDE) of each channel is dependent on the state of polarization of the to-be-detected photons. Here, we report on an eight-channel system with fractal superconducting nanowire single-photon detectors working in the wavelength range of 930-940 nm that all feature low polarization sensitivity. In a close-cycled Gifford-McMahon cryocooler system with the base temperature of 2.2 K, we install and compare the performance of two types of devices: (1) SNSPD, composed of a single, continuous nanowire, and (2) superconducting nanowire avalanche photodetector (SNAP), composed of 16 cascaded units of two nanowires electrically connected in parallel. The highest system detection efficiency (SDE) among the eight channels reaches 96−5+4%, with polarization sensitivity of 1.02 and dark-count rate of 13 counts per second. The average SDE for eight channels for all states of polarization is estimated to be 90 ± 5%. We conclude that both the SNSPDs and the SNAPs can reach saturated, high SDE at the wavelength of interest, and the SNSPDs show lower dark- (false-) count rates while the SNAPs show better properties in the time domain. Using this system, we showcase the measurements of the second-order photon-correlation functions of light emission from a single-photon source based on a semiconductor quantum dot and from a pulsed laser. We believe that our work provides new choices of systems with single-photon detectors combining the merits of high SDE, low polarization sensitivity, and low noise that can be tailored for different applications.

Transition from anisotropic to isotropic optical absorption in core-shell square nanowires tuned by anti-crossing engineering.

The transition from anisotropic to isotropic optical properties in nanostructures plays an important role in developing next-generation intelligent photonic devices. Currently, core-shell nanostructures, frequently accompanied by different growth rates, are typically characterized by anisotropic optical properties at mid-infrared wavelengths. This inherent anisotropy, however, poses formidable challenges in achieving optical isotropy. In this work, an electric field is employed to transform the optical anisotropy of the off-centered core-shell square nanowires into optical isotropy. Based on the finite difference method, the results show that by tuning the electric field reasonably, the anti-crossing behavior of energy levels can be induced to align the energy structures in both eccentric and concentric nanowires. Although the optical anisotropy is strongly dependent on the distance and direction of the core shift, we marks, to the best of our knowledge, the first demonstration that the restored electronic states can effectively neutralize the polarization sensitivity, achieving isotropic optical absorption with wavelengths longer than 10 μm. Our finding indicates that the anti-crossing behavior of energy levels can serve as a viable mechanism to achieve switchable optical isotropy.

A compact single‐layer reflective metasurface for high‐efficiency polarisation conversion applications in C and X bands

AbstractThe authors design and experimentally analyse an anisotropic metasurface for the simultaneous conversions of linear cross and circular polarisations in the C and partial X bands. The proposed compact structure utilises a dual‐cut square‐ring resonator and a square patch on an FR4 substrate above a ground plane. The full‐wave simulations exhibit over 92% efficiency in cross‐conversion over a fractional bandwidth (BW) of 52.3%. The proposed metasurface efficiently converts linear to circular polarisation in two different bands, achieving left‐hand circularly polarised and right‐hand circularly polarised efficiencies exceeding 93% and 89%, respectively. The compact unit‐cell with dimension 0.22λ × 0.22λ attains stable polarisation transformation efficiency rates exceeding 80% up to 40° incident angles. The design is adaptable for efficient wide BW across both lower and higher (millimetre‐wave) frequencies through scaling. A prototype of the proposed polarisation converter (PC) was realised and validated effectively in measurements, aligning well with simulations. This PC features a novel and simple structure with multifunctional wideband operation, stable incident angle output, polarisation insensitivity, and scalability, making it an efficient front‐end for various radio frequency applications, including polarisation control and polarisation transformers.

A low-frequency ultrathin metamaterial absorber using magnetic material

In this paper, an ultra-thin metamaterial absorber (UMA) in the S-band is designed. The overall structure adopts a three-layer design. The top layer is a magnetic material, and the middle layer of the UMA is composed of a centrally symmetrical open square ring (four edges are opened) and a circular pattern placed at the center, which is etched on the FR4 dielectric substrate by printed circuit board technology. The absorptivity of the absorber is more than 90% in 1.73–4.04 GHz under normal incidence, and the fractional bandwidth is 80.1%. The total thickness of the absorber is about 3.4 mm, corresponding to 0.02 λL at the lowest operating frequency. Moreover, it also has good polarization insensitivity and wide-angle incident characteristics. The absorption mechanism of the UMA is analyzed from the aspects of power loss density and surface current. Finally, a sample was fabricated and measured. The measured results are in good agreement with the simulation results, which verifies the effectiveness of the design method.

Predicting nonradiative decay barrier of BODIPY dye in polar environment by applying ONIOM multiscale method

Fluorescent molecular sensors are widely used in biological research. They allow straightforward viscosity, temperature or polarity measurements at the microscopic level, including live cells. Maps of desired physical properties can be obtained by applying fluorescence lifetime imaging microscopy (FLIM) to cells. One of the most important properties of a cell is viscosity, as it affects other parameters, such as the rate of biochemical reactions and particle diffusion. Boron-dipyrromethene (BODIPY) compounds are widely used for viscosity measurements, but current variants have the undesirable sensitivity to polarity, and more suitable alternatives are being sought using theoretical computations. The polarizable continuum model (PCM) used in previous studies did not adequately take into account the influence of the polar environment when calculating the BODIPY activation energy associated with polarity sensitivity. After applying the multilayer ONIOM method in polar and non-polar environments, the calculated maximum wavelengths of the fluorescence spectra of the 8PhBODIPY compound were closer to the experimental results compared to PCM. The activation energy was also calculated, its value in polar and non-polar environments qualitatively corresponded to the experimental results, and the quantitative agreement was reached using the empirical correction.

Short‐Wave Infrared Photodetectors Based on β‐In2Se3/Te Heterojunctions for Optical Communication and Polarimetric Imaging Applications

AbstractPolarization‐sensitive infrared photodetectors have vast application prospects in imaging systems and polarization sensors due to the addition of new detection dimensions beyond wavelength and intensity. However, most polarization‐sensitive photodetectors are operated in the visible wavelength range and still encounter challenges of limited responsivity (R) and polarization ratio (PR) under short‐wave infrared illumination. To address these issues, a vertical heterostructure of β‐In2Se3‐on‐Te is reported, achieving high‐performance and polarization‐sensitive imaging sensors in the short‐wave infrared (SWIR) region. The high R (2 A/W at 1310 nm and 0.71 A/W at 1550 nm) and specific detectivity (2.14 × 109 Jones at 1310 nm and 7.3 × 108 at 1550 nm) are obtained, which surpasses most photodetectors using anisotropic 2D material in the infrared range. Considering the strong anisotropic nature of Te nanosheets, the device exhibits notable polarization sensitivity with a PR value of 4.95 under 1310 nm laser irradiation. This work proposes a multifunctional photodetector for the great applications of ASCII code transmission and polarization‐sensitive infrared imaging, offering a new opportunity for versatile angle‐resolved optoelectronics in the infrared communication band.

Patterned Chiral Perovskite Film for Self‐Driven Stokes Photodetectors

AbstractPolarization detection plays an essential role in a wide range of fields, including target identification, 3D reconstruction, and robotic vision. Self‐driven on‐chip full‐Stokes photodetectors are urgently required to meet the trend of miniaturization and integration. Nevertheless, how to fulfill efficient circular and linear polarimetry simultaneously with sufficient recognition effectiveness in a compact device is a great challenge. Herein, a patterned chiral perovskite film is fabricated by imprinting strategy, and vertically‐structured self‐driven Stokes photodetector is demonstrated, which can recognize various polarization states at 0 V. Through patterned design of the chiral perovskite film by integrating circle and nanowire structure, flexible tuning of circular and linear polarization components within the detector is achieved, enabling the detector to strike a balance between circular and linear polarization detection ability when recognizing arbitrary polarization light. The maximum circular polarization sensitivity factor and linear polarization ratio can reach 0.125 and 1.5, respectively. By optimizing well‐defined patterned shape, the resultant detector can recognize polarized light with an average recognition error <7%. This work opens an avenue toward the fabrication of self‐driven filterless Stokes detectors based on patterned chiral perovskite film for accurate detection of arbitrary polarization states.

Mid-infrared bimodal wide metamaterial absorber based on double-layer silicon nitride structure

Infrared band occupies a very important position in the electromagnetic wave band. Traditional infrared devices use the inherent properties of natural materials to achieve the regulation of electromagnetic waves, but the limited ability of such devices to regulate electromagnetic waves can't well meet our needs. In this paper, we reported a metamaterial absorber of Cr-Si3N4-Cr-Si3N4-Ti based on double-layer metal-insulator-metal (MIM). It is investigated with the optimal structural parameters of 490 nm, 330 nm, 30 nm, 720 nm, 120 nm, in descending order, at which the absorptive properties are studied. When the light wave is incident vertically, it can be obtained from the experimental simulation that this absorber has polarisation insensitivity. Because of the coupling effect of the surface plasmon resonance and the high-loss material, the bandwidth of absorption greater than 90% can reach 9190 nm, and the average absorption in the target long-wave infrared band (9.506∼18.145 μm) is 94.8%. By selecting different geometrical parameters of the structure, the absorption spectrum can be adjusted independently. In addition, the absorber has good incident angle insensitivity in TE and TM modes. Also, the absorber we proposed has a plain structure, is convenient for manufacturing, the material is easier to obtain, which ensures a good absorption bandwidth and average absorptivity, and the study of this metamaterial absorber has important applications in solar cells, satellite radiothermographs, photodetectors, and spectral imaging.

Polarisation vision in the dark: green-sensitive photoreceptors in the nocturnal ball-rolling dung beetle Escarabaeus satyrus.

Many insects utilise the polarisation pattern of the sky to adjust their travelling directions. The extraction of directional information from this sky-wide cue is mediated by specialised photoreceptors located in the dorsal rim area (DRA). While this part of the eye is known to be sensitive to the ultraviolet, blue or green component of skylight, the latter has only been observed in insects active in dim light. To address the functional significance of green polarisation sensitivity, we define the spectral and morphological adaptations of the DRA in a nocturnal ball-rolling dung beetle-the only family of insects demonstrated to orient to the dim polarisation pattern in the night sky. Intracellular recordings revealed polarisation-sensitive green photoreceptors in the DRA of Escarabaeus satyrus. Behavioural experiments verified the navigational relevance of this finding. To quantify the adaptive value of green sensitivity for celestial orientation at night, we also obtained the polarisation properties of the night sky in the natural habitat of the beetle. Calculations of relative photon catch revealed that under a moonlit sky the green-sensitive DRA photoreceptors can be expected to catch an order of magnitude more photons compared with the UV-sensitive photoreceptors in the main retina. The green-sensitive photoreceptors - which also show a range of morphological adaptations for enhanced sensitivity - provide E. satyrus with a highly sensitive system for the extraction of directional information from the night sky.

Ultra-wideband absorber based on graphene surface with polarization insensitivity under large angles

In this paper, a frequency-selective absorber with large-angular stability under oblique incidence is present. The absorptivity of the structure can be reached to maximum by impedance matching and parameter optimization method under a specific angle (40°), which ensures an excellent absorption response within 60° oblique incidence. This method solves the problem that the absorptivity of traditional absorbers deteriorates with the increase of incident angle. The absorber consists of a three-layer structure: two lossy layers and a metal ground layer, the equivalent circuit model is discussed and the operating frequency band is widened by generating electric resonances and magnetic resonances. Due to the high symmetry of the structure, the absorber has good polarization insensitivity. Numerical simulation shows that from 4.4 to 20 GHz, the absorptivity of the structure is above 90% within 40° oblique angle of incidence. Finally, the design plays an important role in military stealth and preventing electromagnetic interference.

Demonstration of nuclear gamma-ray polarimetry based on a multi-layer CdTe Compton camera

To detect and track structural changes in atomic nuclei, the systematic study of nuclear levels with firm spin-parity assignments is important. While linear polarization measurements have been applied to determine the electromagnetic character of gamma-ray transitions, the applicable range is strongly limited due to the low efficiency of the detection system. The multi-layer Cadmium-Telluride (CdTe) Compton camera can be a state-of-the-art gamma-ray polarimeter for nuclear spectroscopy with the high position sensitivity and the detection efficiency. We demonstrated the capability to operate this detector as a reliable gamma-ray polarimeter by using polarized 847-keV gamma rays produced by the 56Fe\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{56}\ extrm{Fe}$$\\end{document}(p,p′γ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${ p},{ p'}\\gamma $$\\end{document}) reaction. By combining the experimental data and simulated calculations, the modulation curve for the gamma ray was successfully obtained. A remarkably high polarization sensitivity was achieved, compatible with a reasonable detection efficiency. Based on the obtained results, a possible future gamma-ray polarimetery is discussed.

A Novel Ultra-Miniaturized Angularly Stable Frequency Selective Surface for L-Band Shielding Applications

This paper presents a novel ultraminiaturized frequency selective surface (FSS) for L-band electromagnetic shielding applications. A basic square loop incorporated with folded arms in the top layer constructs the single-layer FSS design. Band-stop characteristics for the entire L-band operating frequency ranging from 1 GHz to 2 GHz are offered by the proposed design. An ultraminiaturized profile of 0.028λο × 0.028λο is achieved by the designed FSS, where λο corresponds to the lowest operating frequency, achieving at least 32.1% miniaturization when compared to the state-of-the-art FSS designs in the literature. Polarization insensitivity with a peak shielding effectiveness of 45.4 dB is manifested by the rotational symmetry of the proposed design. The proposed FSS exhibits excellent angular stability performance up to 80° with a frequency deviation of less than 1%. The equivalent circuit model helps to understand the working principle of the proposed FSS. The experimental results of the designed FSS prototype agree well with the simulation results. Hence, the proposed spatial filter is a suitable candidate for enhancing security in wireless communication at the carrier frequencies of GPS systems.

Polarization‐Sensitive and Self‐Driven Pyro‐Phototronic Photodetectors Based on MoS2‐Water Heterojunctions

AbstractPolarization‐sensitive and self‐driven pyroelectric‐based photodetectors have recently gained interest due to their potential application in artificial electronic eyes, biomedical imaging, and optical switches. Here, a photodetector based on light modulation‐induced polarization and depolarization of water molecules on the surface of a 2D MoS2 crystal is reported. The MoS2‐water heterostructure photodetector serves as a self‐driven pyro‐phototronic device that converts light‐induced thermal energy to electrical signals, leading to a transient photoresponsivity as high as 24.6 mA W−1 and a specific detectivity of 2.85 × 108 Jones under 470 nm wavelength at zero bias. Due to the formation of a built‐in electric field at the MoS2‐water interface, this structure also has a high steady–state responsivity of 3.62 A W−1 and detectivity of 9.18 × 108 Jones at 3 V bias, along with a fast response time of ≈0.74 ms. Moreover, due to the rearrangement of the hydrogen bond network in the liquid water upon visible light illumination, the MoS2‐water photodetector is light polarization‐sensitive. The simple fabrication process, low cost, polarization sensitivity, and high performance of the MoS2‐water structure make it an excellent candidate for liquid‐compatible photodetectors.

Three-in-one polarization detector enabled by metasurface

In the field of biomedicine, the detection of target analytes imposes requirements on polarization information detection and sensitivity. It necessitates non-destructive analysis of proteins and DNA. The combination of dielectric geometric metasurface with terahertz (THz) vortex beams present new opportunities for biomedical sensing. In this work, we employ simulation to demonstrate a novel methodology that integrates off-axis dual-focus with vector vortex beams (VVB). Moreover, the metasurface-based method provides potential solutions for miniaturized polarization detection. The capability of polarization detection is evaluated using different polarization states at three different focal planes. Specifically, the ellipticity and handedness of incident THz waves can be determined by the electric field intensity ratio of the two off-axis focused spots. The major axis direction of linear polarization waves can be determined by extracting the azimuth of the VVB. It is worth mentioning that higher-order VVB, benefiting from its high angular resolution characteristics, exhibits enhanced sensitivity in determining the direction of major axes. Our proposed scheme offers potential applications for THz communications, medical imaging, security detection and remote sensing.