Polarization-sensitive Characteristics Research Articles

(Invited) Phase Engineering for Enhanced Stability of Perovskite Nanowire Optoelectronics

The crystallization of halide perovskites (HPs) into one-dimensional structures has generated considerable research interest for their promising prospects in studying electron transport characteristics and multifunctional nanoscale devices. Various strategies have been developed to achieve in-plane growth of one-dimensional (1D) structures, including epitaxy, capillary-bridge-manipulated graphoepitaxy, and van der Waals epitaxy. Typically, the VLS growth mode, which involves the initial seeding of metallic catalytic nanoparticles to facilitate the process, has realized the out-of-plane and bottom-up synthesis route, opening up a new pathway for the one-dimensional perovskite electronics and optoelectronics.Among many recent advances, Zinc (Zn) has become a significant suppressor of vacancy formation in halide perovskites, establishing its pivotal role in defect engineering for these materials. Herein, we report the Zn-catalyzed vapor-liquid-solid (VLS) route to render black-phase CsPbI3 nanowires operationally stable at room temperature. Based on first-principle calculations, the doped Zn2+ can not only lead to the partial crystal lattice distortion but also reduce the formation energy value from the black phase to the yellow phase, improving the stability of the desired black phase. A series of contrast tests further confirm the stabilization effect of the Zn-doped strategy. Besides, the polarization-sensitive characteristics of black phase CsPbI3 nanowires were revealed. Our work highlights the importance of phase stabilization engineering for CsPbI3 nanowires and their potential applications in anisotropic optoelectronics.

Sub-micron pixel polarization-sensitive photodetector based on silicon nanowire

Silicon nanowire is a potential candidate to be used as polarization-sensitive material, but the relative mechanism of polarization response must be carried out. Herein, a sub-micron metal-single silicon nanowire-metal photodetector exhibits polarization-sensitive characteristics with an anisotropic photocurrent ratio of 1.59 at 780 nm, an excellent responsivity of 24.58 mA/W, and a high detectivity of 8.88 × 109 Jones at 980 nm. The underlying principle of optical anisotropy in silicon nanowire is attributed to resonance enhancement verified by polarizing light microscopy and simulation. Furthermore, Stokes parameter measurements and imaging are all demonstrated by detecting the characteristics of linearly polarized light and imaging the polarizer array, respectively. Given the maturity of silicon processing, the sub-micron linearly polarized light detection proposed in this study lays the groundwork for achieving highly integrated, simplified processes, and cost-effective on-chip polarization-sensitive optical chips in the future.

Metasurface computing components that support dual channel parallel processing and provide full type logic gate options

The logic gate components based on electromagnetic waves are crucial for building a digital computing platform with batch computing and low-cost energy consumption requirements. However, most of the reported logic gates have only one computational channel and have a single function. In order to improve the channel capacity and versatility of logic gates, we design a simple and compact graphene metasurface for dual channel parallel computing, with each channel's function being switchable across all types of logic functions. In the design, we combine the advantages of reconfigurable metasurfaces and polarization sensitive metasurfaces. Based on the polarization sensitive characteristics, we integrate two polarization logic gates into a single device. These two polarization logic gates can work simultaneously, and the crosstalk between them is 0. Based on the reconfigurable feature, the functions of both logic gates can be freely selected from NOT, AND, NAND, OR, NOR, XOR and XNOR. So, this component can achieve simultaneous operation of any two logical functions, and there are 49 combinations available. Our design philosophy provides inspiration for achieving ultra fast and high-density integrated signal processing.

Ultra-broadband infrared metamaterial absorber based on MDMDM structure for optical sensing

Infrared observation is a crucial tool in the study of astronomical celestial bodies. Metamaterials have a vast prospect for applications in the field of optics due to their unique electromagnetic tunable characteristics. In order to obtain an ultra-broadband high absorption material in the infrared region, we proposed a metal-dielectric-metal-dielectric-metal (MDMDM) metamaterial absorber using a titanium (Ti) nano-cross layer based on surface plasmon polariton (SPP) resonance and magnetic resonance cavity principles. The geometrical parameters of each layer have been examined carefully. The influence of incident angle from 0° to 60° is investigated for transverse electric and transverse magnetic plane-waves. Near-perfect absorption performance is achieved from near-infrared to mid-infrared region. The average absorption reaches as high as 97.41% from 2.05 to 6.08 μm. The absorber exhibits polarization-sensitive characteristics. The absorption peaks are 99.50% and 99.80% at 2.55 and 5.24 μm, respectively. The proposed material has potential applications in astronomical imaging, volcano and fire detection, remote sensing, biological monitoring, and other optical devices.

Anisotropic programmable metasurface beam splitter based on diode real-time control

we propose an anisotropic programmable coding metasurface, which is composed of digital coding elements integrated with PIN diode. The "0″ and "1″ states of the diode are controlled in real time by external voltages, and a single metasurface unit is controlled by the FPGA (Field Programmable Gate Array). Due to the polarization-sensitive characteristics, it is not only possible to switch the polarization states in the orthogonal two directions separately, but also to realize the remote scattering control at any angle by means of convolution coding. The metasurface can be converted on polarization (linear polarization or circular polarization) by means of real-time coded modulation. We further experimentally prepared a diode based programmable coding metasurface and measured the angle of far-field scattering using a microwave test system. The independent polarization wavefront control greatly enhances the channel capacity of metasurface, and programmable metasurface has a higher degree of freedom when multifunction modulation is realized.

A quintuple plasmon-induced transparency multifunction switch based on the polarization-sensitive graphene-based metamaterial

A monolayer metamaterial consisting of a rectangle graphene strip and four L-shaped graphene blocks was proposed to achieve a quintuple plasmon-induced transparency (quintuple-PIT). The numerical simulation results based on the finite difference time domain method agree well with the calculated results of the coupled mode theory. By modulating the Fermi energy level of graphene, an octuple-frequency asynchronous switch and a sextuple-frequency synchronous switch are designed and studied, which have excellent amplitude modulation degree (up to 97.7%), extinction ratio (up to 16.41 dB), insertion loss (low to 5.4%), and dephasing time(low to 3.86 ps). Furthermore, the results show that the proposed metamaterials has polarization-sensitive characteristics due to their non-central symmetry. Further research shows that the group index is as high as 604 which has a good slow light effect and can be used for optical storage. Hence, the quintuple-PIT proposed structure in this paper has good application value in the expansion of multi-function optical switches and the research of high-quality optical memory.

High-Responsivity Multiband and Polarization-Sensitive Photodetector Based on the TiS3/MoS2 Heterojunction.

Two-dimensional (2D) material photodetectors have received considerable attention in optoelectronics as a result of their extraordinary properties, such as passivated surfaces, strong light-matter interactions, and broad spectral responses. However, single 2D material photodetectors still suffer from low responsivity, large dark current, and long response time as a result of their atomic-level thickness, large binding energy, and susceptibility to defects. Here, a transition metal trichalcogenide TiS3 with excellent photoelectric characteristics, including a direct bandgap (1.1 eV), high mobility, high air stability, and anisotropy, is selected to construct a type-II heterojunction with few-layer MoS2, aiming to improve the performance of 2D photodetectors. An ultrahigh photoresponsivity of the TiS3/MoS2 heterojunction of 48 666 A/W at 365 nm, 20 000 A/W at 625 nm, and 251 A/W at 850 nm is achieved under light-emitting diode illumination. The response time and dark current are 2 and 3 orders of magnitude lower than those of the current TiS3 photodetector with the highest photoresponsivity (2500 A/W), respectively. Furthermore, polarized four-wave mixing spectroscopy and polarized photocurrent measurements verify its polarization-sensitive characteristics. This work confirms the excellent potential of TiS3/MoS2 heterojunctions for air-stable, high-performance, polarization-sensitive, and multiband photodetectors, and the excellent type-II TiS3/MoS2 heterojunction system may accelerate the design and fabrication of other 2D functional devices.

Terahertz meta-absorber with tunable single- and dual-resonance characteristics

A design of tunable terahertz (THz) meta-absorber (TMA) is proposed, which is composed of a periodic Al cross-shaped resonator suspended on bottom Al mirror layer. The electromagnetic responses of TMA can be manipulated between single- and dual-resonance. TMA shows polarization dependent and independent characteristics. Moreover, the flexibility and applicability of TMA are highly improved as it exhibits the linear red-shifting of resonances by increasing the environmental refraction index. The highest sensitivity is 3.05 THz/RIU. This design of tunable TMA provides a useful method for the applications in solar cells, optical switching , imaging, energy harvesting , and high-sensitive sensing in the THz-wave optoelectronics fields. • A design of tunable terahertz (THz) meta-absorber (TMA) is proposed. • The electromagnetic responses can be manipulated between single- and dual-resonance. • TMA shows polarization sensitive characteristic. • TMA exhibits the linear red-shifting of resonances by increasing the environmental refraction index. • TMA shows high sensitivity of 3.05 THz/RIU for ω 2 resonance.

Polarization-sensitive optical Tamm state and its application in polarization-sensitive absorption

In conventional heterostructures consisting of metal layers and all-dielectric one-dimensional (1-D) photonic crystals (PCs), optical Tamm states (OTSs) shift toward shorter wavelengths (i.e., blueshift) as the incident angle increases for both transverse magnetic (TM) and transverse electric (TE) polarizations. Such celebrated polarization-insensitive characteristic of OTSs poses a great challenge in achieving polarization-sensitive absorption. Herein, we realize an anomalous OTS with polarization-sensitive characteristic in a heterostructure consisting of a metal layer and a 1-D PC containing hyperbolic metamaterials. As the incident angle increases, the designed OTS is redshifted for TM polarization while is blueshifted for TE polarization. The polarization-sensitive characteristic of the OTS can be explained by the phase analysis. Assisted by the designed OTS, polarization-sensitive absorption can be achieved. Our work provides a platform to engineer the angle-dependence of OTSs and would promote the development of absorption-based applications.

Wide-angle polarization selectivity based on anomalous defect mode in photonic crystal containing hyperbolic metamaterials.

Conventional defect modes in all-dielectric 1D photonic crystals (PCs) are polarization-insensitive. This poses a great challenge in achieving high-performance polarization selectivity. In this Letter, we introduce a defect layer into a 1D PC containing hyperbolic metamaterials to achieve an anomalous defect mode with polarization-sensitive characteristics. As the incident angle increases, such a defect mode remains almost unshifted under transverse magnetic polarization, while strongly shifting toward shorter wavelengths under transverse electric polarization. The polarization-sensitive characteristics of the defect mode can be well explained by the Fabry-Perot resonance condition. Assisted by the polarization-sensitive defect mode, wide-angle polarization selectivity with an operating angle width up to 54.8° can be realized. Our work provides a route to designing wide-angle linear polarizers using simple 1D structures, which would be useful in liquid crystal display and Q-switched lasers.

The Orientation Estimation of Elongated Underground Objects via Multipolarization Aggregation and Selection Neural Network

The horizontal orientation angle and the vertical inclination angle of an elongated subsurface object are key parameters for object identification and imaging in ground-penetrating radar (GPR) applications. Conventional methods can only extract the horizontal orientation angle or estimate both angles in narrow ranges due to limited polarimetric information and detection capability. To address these issues, this letter, for the first time, explores the possibility of leveraging neural networks with multipolarimetric GPR data to estimate both angles of an elongated subsurface object in the entire spatial range. Based on the polarization-sensitive characteristic of an elongated object, we propose a multipolarization aggregation and selection network (MASNet), which takes the multipolarimetric radargrams as inputs, integrates their characteristics in the feature space, and selects discriminative features of reflected signal patterns for accurate orientation estimation. Numerical results show that our proposed MASNet achieves high estimation accuracy with an angle estimation error of less than 5°. The promising results obtained by the proposed method encourage one to think of new solutions for GPR-related tasks by integrating multipolarization information with deep learning techniques. The data and code implemented in the letter can be found at <uri xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">https://haihan-sun.github.io/GPR.html</uri> .

Tunable terahertz double split-ring metamaterial with polarization-sensitive characteristic

We propose a design of tunable double split-ring metamaterial (DSRM) in the terahertz (THz) frequency range. It is composed of a H-shaped resonator sandwiched by two face-to-face split-ring resonators (SRRs) on silicon on insulator (SOI) substrate. The electromagnetic responses of DSRM can be manipulated between single-resonance and dual-resonance by changing the incident polarization light, which shows polarization sensitive characteristic. DSRM exhibits a tunable function in the frequency range of 0.16 THz to 0.21 THz through enlarging the gap within two SRRs at TE mode. DSRM also shows stable characteristic by changing the distance between two face-to-face SRRs at TE and TM modes. Furthermore, to enhance the flexibility and applicability of DSRM, it is exposed on the surrounding environments with different refraction indexes. The correction coefficients are 0.997 for DSRM at TE and TM modes. These results show that DSRM exhibit the linear red-shifting of resonances by increasing the environmental refraction index. This work paves a way to the possibility of metamaterial devices with great tunability and polarization-dependence characteristics in the sensing applications.

Simulated and experimental verification of the microwave dual-band metamaterial perfect absorber based on square patch with a 450 diagonal slot structure

In this paper, we designed a dual band metamaterial perfect absorber (MPA) for Ku band applications. The overall ultrathin layer of proposed absorber consists of square patch with 450 diagonal slot structure within a copper square patch which loaded on both sides of dielectric thickness 1.6 mm FR-4 substrate. The results show that designed MPA gives two absorption bands at 12.45 and 14.18 GHz and absorption rates are 99.73% and 99.87% respectively. The proposed dual-band absorber has a polarization sensitive characteristic, the absorption performance is almost changing with different polarization angles. Furthermore, resonance centres of two absorption bands can be adjusted by changing related parameters. The novelties of proposed structure are simple, easy fabricate, low cost, durable, suitable for real-time applications and long-term stability considering the fabrication technique and non-destructive measurement method. The dualband absorber can be used in practical applications such as bolometer, EM wave spatial filter and satellite communications.

Van der Waals heterojunction ReSe2/WSe2 polarization-resolved photodetector

Polarization-resolved photodetectors, a significant branch of photodetection, can more effectively distinguish the target from the background by exploiting polarization-sensitive characteristics. However, due to the absence of intrinsic polarized absorption properties of many materials, there is still a great challenge to develop the high-performance polarization-resolved photodetectors. Here, we report a van der Waals heterojunction (vdWH) ReSe2/WSe2 photodetector, which performs a high responsivity of ~0.28 A/W and a high detectivity of 1.1 × 1012 Jones under the illumination of 520 nm laser at room temperature. Remarkably, scanning photocurrent mapping (SPCM) measurements demonstrate the photoresponse of devices closely depend on the polarized angle of the incident light, indicating the effective polarized light detection. This work paves the way to develop high-performance polarization-resolved photodetectors based on two-dimensional (2D) materials.

Measurement of polarization-sensitive characteristic of scientific CCD detector

Polarization measurement accuracy is an important indicator of the polarization remote sensing detection system. In order to effectively analyze the factors that affect the polarization measurement accuracy, it is necessary to analyze the polarization sensitive characteristics of the scientific CCD detector. Taking the 1k*1k area array CCD detector of DALSA Company as the research object, the experimental method of polarization sensitivity detection of scientific grade CCD detector is systematically introduced. The integrating sphere is used as a non-polarized light source, and a polarizer is installed at the light exit port, which defines the degree of polarization sensitivity. Acquired the data through three different methods which are rotated the polarizer at the same time fixed the CCD, the CCD and polarizer coaxial rotated and fixed polarizer while rotated CCD respectively, analyze the obtained data separately. The experiment results show that the polarization sensitive degree of the CCD detector is 0.58, and the polarization sensitivity suppression measures with the addition of the depolarizer assembly are considered. The results show that this method obviously suppresses the polarization sensitivity of the CCD, and its polarization sensitivity is 0.034. The research results have important guiding significance for the development of high-precision polarization detection system and polarization calibration research.

Tunable Terahertz Metamaterial Using an Electric Split-Ring Resonator with Polarization-Sensitive Characteristic

We present a tunable terahertz (THz) metamaterial using an electric split-ring resonator (eSRR), which exhibits polarization-sensitive characteristics. The proposed eSRR is composed of double symmetrical semicircles and two central metal bars. By changing the lengths of two metal bars, the electromagnetic responses can be tuned and switched between dual-band and triple-band resonances in transverse magnetic (TM) mode. Furthermore, by moving the bottom metal bar to change the gap between the two metal bars, the first resonance is stable at 0.39 THz, and the second resonance is gradually blue-shifted from 0.83 to 1.33 THz. The tuning range is 0.50 THz. This means that the free spectrum ranges (FSR) could be broadened by 0.50 THz. This proposed device exhibits a dual-/triple-band switch, tunable filter, tunable FSR and polarization-dependent characteristics. It provides an effective approach to perform tunable polarizer, sensor, switch, filter and other optoelectronics in THz-wave applications.

Tunable microwave sawtooth waveform generation based on one single-drive Mach-Zehnder modulator.

A photonic method of sawtooth waveform generation by using one single-drive Mach-Zehnder modulator is proposed and experimentally demonstrated. Depending on the polarization-sensitive characteristic of the modulator, the modulation sidebands and optical carrier can independently exist on two orthogonal polarization directions. Therefore, the required Fourier components can be manipulated on two polarization dimensions separately, and the superposition of the orthogonal optical envelopes synthesize a sawtooth waveform in time domain. The feasibility of the scheme is theoretically analyzed. In the experiment, sawtooth waveforms with full duty cycle at 3, 5, and 8 GHz are obtained, which agree with the simulation results well.

THz polarization-sensitive characterization of a large-area multilayer rhenium diselenide nanofilm

Recently, rhenium diselenide (ReSe2) has attracted considerable attention due to its high anisotropy in the layer plane, which makes it a promising candidate for wide applications in electronics and optoelectronics. In this paper, we focus on the polarization-sensitive characteristics of a large-area multilayer ReSe2 nanofilm in the terahertz (THz) region under passive and active conditions by means of THz time-domain spectroscopy. We demonstrate the passive ReSe2 nanofilm with intrinsic THz polarization anisotropy. Maximum transmittance occurs only when the polarization direction of the incident THz wave is along the Re-chains direction. More importantly, THz polarization properties of the active ReSe2 nanofilm by an external electric field applied in a selected directions are also demonstrated. The modulation depth of the THz transmission is up to 16% and the response time is on the order of picoseconds. In addition, a comparative experiment is performed on three kinds of THz polarizers, i.e., ReSe2 nanofilm, carbon nanotubes (CNTs) and wire-gird, respectively. The results prove that the performance of the polarizer based on the active ReSe2 nanofilm is comparable with those of CNTs and the THz wire-gird polarizer. Based on these studies, we believe that the polarization-sensitive ReSe2 nanofilm can find important applications in ultrafast switches, filters and modulation devices in the THz region.

Real-time photonic sampling with improved signal-to-noise and distortion ratio using polarization-dependent modulators

A real-time photonic sampling structure with effective nonlinearity suppression and excellent signal-to-noise ratio (SNR) performance is proposed. The key points of this scheme are the polarization-dependent modulators (P-DMZMs) and the sagnac loop structure. Thanks to the polarization sensitive characteristic of P-DMZMs, the differences between transfer functions of the fundamental signal and the distortion become visible. Meanwhile, the selection of specific biases in P-DMZMs is helpful to achieve a preferable linearized performance with a low noise level for real-time photonic sampling. Compared with the quadrature-biased scheme, the proposed scheme is capable of valid nonlinearity suppression and is able to provide a better SNR performance even in a large frequency range. The proposed scheme is proved to be effective and easily implemented for real time photonic applications.

Photonic generation of microwave triangular waveform based on polarization-dependent modulation efficiency of a single-drive Mach–Zehnder modulator

A new photonic approach for triangular waveform generation by making full use of the polarization sensitive characteristic of the single-drive Mach–Zehnder modulator (MZM) is proposed and experimentally demonstrated. In this method, the MZM is biased at minimum transmission point and its best modulation axis has an angle with the polarization direction of injection continuous wave (CW). Due to the polarization dependent modulation efficiency of a MZM, the odd-order modulation sidebands can be generated on the parallel polarization component but only the optical carrier is presented on the orthogonal direction. After a polarizer, the required Fourier components can be projected on the same polarization direction, which contribute a triangular pulse stream by photodetection. In the experimental demonstration, triangular waveforms with repetition frequencies of 8, 10, and 12GHz are successfully generated, respectively.