Horizontal Linear Polarization Research Articles

High-precision two-dimensional displacement metrology based on matrix metasurface.

A long-range, high-precision, and compact transverse displacement metrology is of crucial importance in both industries and scientific researches. However, it is a great challenge to measure arbitrary two-dimensional (2D) displacement with angstrom-level precision and hundred-micrometer range. Here, we demonstrated a prototype of high-precision 2D-displacement metrology with matrix metasurface. Light passing through the metasurface is diffracted into three beams in horizontal (H), vertical (V), and diagonal (D) linear polarization. 2D transverse displacement of the metasurface relative to the incident light beam is retrieved from the interferential optical powers arisen from coherent superposition between H-polarized and D-polarized beams or V-polarized and D-polarized beams. We experimentally demonstrate that arbitrary displacement in 2D plane can be determined with high precision down to 0.3 nm in a large range of 200 micrometers. Our work broadens the application scope of metasurface and paves the way for development of ultrasensitive optical 2D displacement metrology.

A Linearly and Circularly Polarization-Reconfigurable Leaky Wave Antenna Based on SSPPs-HSIW

In this manuscript, a reconfigurable leaky wave antenna is proposed with linearly polarized and circularly polarized properties, which is composed of two layers with feeding waveguide and radiation elements. The bottom layer is a half-mode substrate integrated waveguide etched with a spoof surface plasmon polaritons structure as a high-dispersion feeding waveguide to excite 8 circular patches as radiation elements in the top layer. In a unit element, the horizontal linear polarization (HLP) and right-hand circular polarization (RHCP) radiation are switched using a p-i-n diode crossing a slot of a circular metal patch. HLP performance is achieved as the p-i-n diode is switched off, and RHCP is achieved as the p-i-n diode is switched on. The measured results verify the design theory and the simulated results. Over the working band of 10.4~12.8 GHz, the proposed antenna can radiate scanning beams covering about a 73° region, including the broadside direction with HLP and RHCP.

Pixel Antenna Optimization Using the Adjoint Method and the Method of Moving Asymptote

The pixel concept offers a convenient and efficient method for antenna design. To meet the given specified antenna requirements or constraints, heuristic algorithms are often used to optimize the connection states for the hardwires between pixels, which are usually assumed to have the binary states, “short” or “open”. An alternative optimization strategy is proposed in this work, where the Boolean constraints on the hardwires are first relaxed to continuously tunable resistances and the globally convergent method of moving asymptotes (GCMMA) is applied to optimize the resistances. To speed up the computation, the adjoint method is used to simplify the calculation of the gradient information required in GCMMA. Resistances that are found as being above or below a certain threshold are then judged as “open” or “short”, respectively. Finally, the remaining intermediate resistance states are binarized using the successive exhaustive Boolean optimization (SEBO) method. Four different optimization strategies are proposed in terms of the objective function implemented in GCMMA and whether the second-stage SEBO is iterative or not. Two broadband endfire pixel antennas having horizontal linear polarization and high radiation efficiency are designed and fabricated correspondingly to demonstrate the feasibility of our proposed methods.

Development of an undulator with adjustable horizontal gap and with electromagnet and permanent magnet for rapid polarization switching

An undulator composed of an electromagnet (EM) and a permanent magnet (PM) has been developed to switch rapidly the right- or left-circularly polarized radiation. The polarization switching is achieved using the rapid change of polarity of excitation currents in the EM, which provides a vertical field in a fixed gap. A horizontal field is generated with a PM; the field strength is adjusted on altering its horizontal gaps. In addition to circularly polarized radiation, the structure fulfills the needs of horizontal and vertical linear polarization. In this paper, we discuss the compact structure and show a design to provide soft X-rays for TPS. The design considerations for this magnet include the design concept, magnetic materials, mechanical and coil structure, all of which are discussed in this paper.

Design and characterization of polarization reconfigurable heart shape monopole antenna for 2.4 GHz application

<span>This article represented a heart shape reconfigurable monopole antenna with polarization diversity. The proposed antenna is fed by a 50 Ω microstrip feed line that is printed on a flexible FR-4 (εr=4.4) substrate. The antenna comprises a ring-slot, a cross slot and four positive-intrinsic-negative (PIN) diodes that are soldered on ring slot. Four PIN diodes act as a switch and by controlling these PIN diodes effective current direction is changed hence four various states of polarization are achieved. Four states of polarization such as horizontal linear polarization (H-LP), vertical linear polarization (V-LP), right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) can be switched easily with the help of these PIN diodes and achieved an efficiency of more than 90%. Proposed antenna shows voltage standing wave ratio (VSWR)<2 at all working frequency and -10 dB reflection coefficients (RC) bandwidths (BW) (i.e., S11≤-10 dB) about 32.86% for linear polarization (LP) states while RHCP and LHCP states possess BW of about 31.61% and 31.67% respectively. It also shows axial ratio (AR) BW of 3.41% and 2.44% for RHCP and LHCP, respectively. Besides, the antenna has a well-suited omnidirectional pattern with a positive gain of all working frequency of interest where cross-polarization level is much lower than that of antenna gain.</span>

Analysis of waveguide polarizers using equivalent network and finite elements methods

Current research is dedicated to the development of new theoretical model for guide polarization converter with irises. New created model is derived based on the equivalent circuits and transmission line representations. Specific feature of the model consists in the possibility of account of irises thickness in the simulations by approximate single-mode method. Using equivalent lumped elements of the circuits we obtained general scattering matrices of the polarization transformer for fundamental modes of vertical and horizontal linear polarizations. Besides, numerical simulations and optimization of the device were carried out by finite elements method. Good agreement of obtained optimal sizes and polarization characteristics is observed. Provided by the polarizer phase difference between two orthogonal polarizations falls within range 90°±5° in the operating Ku-band. Calculated ellipticity coefficient is better than 1.5 dB. Developed model can be applied for designing of new waveguide polarization converters, filters and other waveguide components with irises.

Theoretical Study on Generation of Multidimensional Focused and Vector Vortex Beams via All-Dielectric Spin-Multiplexed Metasurface.

The optical vortex (OV) beams characterized by orbital angular momentum (OAM) possess ubiquitous applications in optical communication and nanoparticle manipulation. Particularly, the vortex vector beams are important in classical physics and quantum sciences. Here, based on an all-dielectric transmission metasurface platform, we demonstrate a spin-multiplexed metadevice combining propagation phase and Pancharatnam–Berry (PB) phase. By utilizing a phase-only modulation method, the metadevice can generate spin-dependent and multidimensional focused optical vortex (FOV) under the orthogonally circularly polarized incident light, and it can successfully realize the multiplexed of the above-mentioned FOVs for linearly polarized light. Meanwhile, the superposition of multiple OAM states can also produce vector vortex beams with different modes. Additionally, the evolution process of the electric field intensity profile is presented after the resultant vector vortex beams through a horizontal linear polarization. This work paves an innovative way for generating structured beams, and it provides promising opportunities for advanced applications in optical data storage, optical micromanipulation, and data communication.

Simultaneous Measurement of pH and Temperature with Phase-Shifted Long-Period Fiber Grating Inscribed on High-Birefringence Fiber by CO₂ Laser Pulses.

We propose an optical fiber grating sensor capable of simultaneously measuring pH and temperature based on a phase-shifted long-period fiber grating (PS-LPFG) inscribed on high-birefringence fiber (HBF). The PS-LPFG was fabricated on HBF with CO₂ laser pulses, and a phase shift π was induced by inserting a grating-free fiber region (GFFR) between two identical LPFGs with a grating period of ˜510 μm. The length of the GFFR was set as half of the grating period to induce a π phase shift. With the spectral characteristics of a π-PS-LPFG exhibiting two split attenuation bands, the PS-LPFG written on HBF, which is referred to as the HB-PS-LPFG, can create two polarization-dependent transmission spectra with dual-resonance dips at different wavelengths according to two orthogonal input polarization states, e.g., linear horizontal polarization (LHP) and linear vertical polarization (LVP). For simultaneous measurement of pH and temperature with the fabricated HB-PS-LPFG as a sensor head, the inter-resonance wavelength separation of the dual-resonance dips in each transmission spectrum obtained for an LHP or LVP input signal was exploited as a sensor indicator. By investigating the wavelength changes of the two sensor indicators, which were induced by pH and temperature variations, linear and independent spectral responses to both pH and temperature variations were experimentally confirmed in a pH range from 1 to 11 and a temperature range from 25 to 65 °C. Owing to the unique pH and temperature responses of the fabricated HB-PS-LPFG, ambient variations in pH and temperature could be simultaneously estimated from the measured wavelength changes and sensitivities of the two sensor indicators.

28 GHz dual‐layer substrate integrated waveguide slot array antenna combined with quad‐polarization

This article presents a compact slot array antenna combined with quad-polarization for mm-wave applications. A novel modified short-circuit termination with inclined slot is proposed in this paper and a dual-layer structure has been adopted to achieve miniaturization and also to design a circular polarization feeding network. Two linear polarization feeding networks are designed independently so that four polarization states can be realized. Four polarization states, namely vertical linear polarization, horizontal linear polarization, left hand circular polarization (LHCP), and right hand circular polarization (RHCP) can be switched by feeding corresponding ports. Judging from impedance matching and axial ratio (AR), the antenna exhibits wide bandwidth. The −10 dB impedance bandwidth and 3 dB AR bandwidth are better than 14.2% (26-30 GHz) with gain about 5-8 dBic for both LHCP and RHCP. The linear polarization states have |S11| < −10 dB and a gain of 5-7 dBi over 26.5-29.5 GHz (10.7%). The size of the slot array antenna is 65 × 65 × 1.156 mm and measured results are consistent with simulations.

Quad-polarization reconfigurable holographic artificial impedance surface based on liquid crystal at terahertz band

A novel quad-polarization reconfigurable holographic artificial impedance surface that exploits the tunable dielectric permittivity of nematic liquid crystal is proposed. The arc-shaped strip is introduced and serves as the fundamental element, and further combined with holographic modulation, electromagnetic radiation at the terahertz band is realized. By partitioning the circular surface into several sectors, studies show that just two impedance values for each sector are enough to reconfigure among different polarizations. The presented demonstrator has a radius of 4.3λ 0, where λ 0 is the wavelength in free space at 1.25 THz, and is excited by a monopole. It can be dynamically reconfigured among vertical linear polarization, horizontal linear polarization, right-hand circular polarization, and left-hand circular polarization at the boresight.

직교 입력 편광에 따른 위상 천이 장주기 격자의 pH 및 온도 응답에 관한 연구

In this paper, we demonstrated an optical fiber sensor based on a phase-shifted long-period fiber gratin g (PS-LPFG) that could realize simultaneous measurement of surrounding pH and temperature variations. The PS-LPFG composed of a grating-free fiber region (GFFR) in the middle of two identical LPFGs was fabricated on high-birefringence fiber (HBF) with CO₂ laser pulses. In addition, a π phase shift formed by setting the length of the GFFR as half of the grating period of an LPFG allows a transmission dip to split into two attenuation bands at two different resonance wavelengths. Since HBF can preserve a linear state of polarization (SOP) if the input SOP is aligned with one of its two principal axes (fast or slow axis), a PS-LPFG inscribed on HBF (HB-PS-LPFG) can create two different transmission spectra for two orthogonal input SOPs, i.e., linear horizontal polarization (LHP) and linear vertical polarization (LVP). To investigate pH and temperature responses of the fabricated HB-PS-LPFG, the dip wavelength separation bet ween two different attenuation bands was used as a sensor indicator for an LHP or LVP input SOP. Consequently, pH- and temperature-induced wavelength variations of the two sensor indicators showed linear and independent spectral responses to both pH and temperature variations in a pH range from 3 to 11 and a temperature range from 25 to 65 °C. With these unique pH or temperature responses of the two sensor indicators, the fabricated sensor could realize simultaneous measurement of pH and temperature.

Polarimetry of soil and vegetation in the visible II: Mueller matrix decompositions

In this paper Mueller polarimetry is applied to study some natural scatter scenes in visible: soil, sand, clay and moss. To obtain the anisotropic and depolarizing properties of the samples under study, the existing additive and multiplicative decompositions of experimental Mueller matrices were used.It is shown that all samples are characterized by anisotropic depolarization: the highest depolarization is observed for the input right and left circular polarizations, the smallest - for the input vertical and horizontal linear polarizations. The anisotropic properties of the samples under study are characterized by linear phase and amplitude anisotropy.

Simultaneous Measurement of Liquid Level and Temperature Using In-Fiber Grating-Based Mach-Zehnder Interferometer and Faraday Rotator Mirror.

Here we propose an optical fiber sensor capable of simultaneous measurement of liquid level and temperature by utilizing cascaded long-period fiber gratings (LPFGs) inscribed on high-birefringence fiber (HBF) and a Faraday rotator mirror (FRM). Due to the in-fiber Mach-Zehnder interference and birefringence of the HBF, these cascaded LPFGs have polarization-dependent discrete interference spectra, each of which is created within one of the two different attenuation bands obtained in the two orthogonal input polarization states, e.g., linear horizontal polarization (LHP) and linear vertical polarization (LVP). The minimum transmittance dip was selected as a sensor indicator for each interference spectrum obtained for LHP or LVP input signal. To monitor these indicator dips associated with LHP and LVP, referred to as the IDH and IDV, respectively, with one spectral scanning, an FRM was connected to the end of the cascaded LPFGs. Both the IDH and IDV spectrally shifted according to liquid-level or temperature changes and showed very linear responses to them with adjusted R₂ values greater than 0.997. The liquid-level sensitivities of the IDH and IDV were measured as approximately -37.29 and -121.08 pm/mm in a liquid-level range of 0 to 55 mm, respectively. The temperature sensitivities of the IDH and IDV were measured as ˜28.79 and ˜218.21 pm/°C in a temperature range of 30 to 60 °C, respectively. Owing to their linear and independent responses to liquid level and temperature, our sensor can perform temperature-independent liquid-level measurement using their pre-determined liquid-level and temperature sensitivities, even if both liquid level and temperature change simultaneously.

Wideband Frequency Agile and Polarization Reconfigurable Antenna for Wireless Applications

In this article, a polarization reconfigurable concentric circle microstrip antenna with simultaneous frequency agility has presented. The frequency agility and polarization reconfigurability have been controlled by open stub cascaded branch-line coupler (OSCBLC) feed network configuration. The −10 dB tunable impedance bandwidth of 2.0 GHz to 3.0 GHz (40%) is achieved by varying the capacitance of four varactor diodes from 4.15pF (0 V) to 0.84pF (7.5 V). These varactor diodes are fixed between the circular patch and ring. The polarization is reconfigured by directing the input RF through a single pole 4 throw (SP4 T) and routed to a single pole double throw (SPDT) switch in the feed network configuration. The right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) are realized in the antenna by exciting the feed ports with a time phase difference of ± 90°. Similarly, the vertical linear polarization (V-LP) and horizontal linear polarization (H-LP) are attained in the antenna by excited any one port through the feed network. The impedance bandwidth (1.5 GHz to 3.5 GHz) of OSCBLC feed network configuration is well-matched with the agile wide impedance bandwidth of the designed antenna. The proposed designed antenna shows good agreement between simulated and measurement results for polarization reconfigurability and frequency agility.

Investigation of C-Band SAR Polarimetry for Mapping a High-Tidal Coastal Environment in Northern Canada

Synthetic Aperture Radar (SAR) has been used in characterizing intertidal zones along northern Canadian coastlines. RADARSAT-2, with its full polarimetric information, has been considered for monitoring these vulnerable ecosystems and helping enhance the navigational safety of these waters. The RADARSAT Constellation Mission (RCM) will ensure data continuity with three identical SAR satellites orbiting together, providing superior revisit capabilities. The three satellites are equipped with multiple configurations, including single-polarization (HH, HV, VV), conventional (HH-HV, VV-VH, and HH-VV), hybrid (i.e., compact) dual polarization, and fully polarimetric (FP) modes. This study investigates the potential of the compact polarimetric (CP) mode for mapping an intertidal zone located at Tasiujaq village on the southwest shore of Ungava Bay, Quebec. Simulated RCM data were generated using FP RADARSAT-2 images collected over the study site in 2016. Commonly used tools for CP analysis include Raney m-delta classification and the hybrid dual polarizations RH-RV (where the transmitter is right-circular and the receivers are horizontal and vertical linear polarizations) and RR-RL (where the transmitter is right circular and the receivers are right-circular and left-circular polarizations). The potential of CP is compared with single, conventional dual-pol, and FP. The Freeman–Durden and Touzi discriminators are used for FP analysis. The random forest classifier is used as a classification approach due to its well-documented performance compared to other classifiers. The results suggest that the hybrid compact (RR-RL and RH-RV) dual polarizations provide encouraging separability capacities with overall accuracies of 61% and 60.7%, respectively, although they do not perform as well as conventional dual-pol HH-HV (64.4%). On the other hand, the CP polarimetric m-delta decomposition generated slightly less accurate classification results with an overall accuracy of approximately 62% compared to the FP Freeman–Durden (67.08%) and Touzi discriminators (71.1%).

Demonstration of variable polarized coherent terahertz source

We are developing an accelerator-based terahertz source that can produce arbitrary polarization states from a linearly polarized coherent undulator radiation (CUR). The polarization manipulation of the CUR can be realized using the Martin–Puplett interferometer employed as an optical phase shifter. This study also demonstrates a variable polarization manipulator by using the terahertz CUR (THz-CUR) source driven by a compact photocathode RF-gun at the Institute of Advanced Energy, Kyoto University. The vertically polarized CUR with a frequency of 0.16 THz was manipulated into a horizontal linear polarization or circular polarization, and Stokes parameters were measured to derive the degree of polarization.

편광 유지 광자 결정 광섬유에 제작한 장주기 광섬유 격자를 이용한 광섬유 비틀림 센서

In this paper, we demonstrated a fiber-optic torsion sensor capable of discriminating twist direction using a long-period fiber grating(LPFG) inscribed on polarization-maintaining photonic cystal fiber(PMPCF) by CO₂ laser pulses. The LPFG written on PMPCF, referred to as the PMPC-LPFG, has a polarization-dependent resonance dip, and two resonance dips are obtained for orthogonal input polarization states designated here as linear horizontal polarization(LHP) and linear vertical polarization(LVP). The torsion responses of these two resonance dips were investigated in a twist angle range from -160° to 160°. When the transmittance of the fabricated PMPC-LPFG, measured on a logarithmic scale, was converted to the transmittance represented on a linear scale, the torsion responses of both dips showed high linearity with an adjusted R<SUP>2</SUP> value greater than 0.99596 in a twist angle range from -160° to 160°. In addition, the temperature response was also examined in a temperature range from 40 to 80℃. The experimental results show that our PMPC-LPFG-based torsion sensor can distinguish torsion direction with excellent linearity and can also offer temperature-insensitive torsion measurement.

편광상이 고리 기반 광섬유 다파장 필터의 입력 편광으로 제어되는 채널 간격 스위칭에 대한 연구

In this paper, we propose an optical fiber multiwavelength filter based on a polarization-diversified loop (PDL), whose channel spacings (CSs) can be controlled by its input state of polarization (SOP). The PDL-based filter consists of a polarization beam splitter, three half-wave plates (HWPs), a Faraday rotator (FR), and two polarization-maintaining fiber (PMF) segments with equal birefringence and different lengths. At proper orientation angle sets (θ<SUB>h1</SUB>, θ<SUB>h2</SUB>, θ<SUB>h3</SUB>) of the three HWPs, the proposed filter can have its polarization-dependent transmittance, offering the CS-switchable operation realized by switching between two orthogonal input SOPs of linear horizontal polarization (LHP) and linear vertical polarization (LVP). In particular, at a fixed input SOP, a half-period wavelength switching operation, i.e., an interleaving operation, can also be implemented by controlling only one HWP angle (θ<SUB>h1</SUB> or θ<SUB>h3</SUB>). Theoretical prediction was verified by experiments. For orthogonal input SOPs of LHP and LVP, the fabricated PDL-based filter could provide transmission spectra with CSs of ∼0.9 and ∼0.3nm or vice versa at appropriate sets of (θ<SUB>h1</SUB><SUB></SUB>, θ<SUB>h2</SUB>, θ<SUB>h3</SUB>), respectively, and each of the transmission spectra could be interleaved by adjusting only θ<SUB>h1</SUB> or θ<SUB>h3</SUB>.

Polarization-diversified-loop-based optical fiber interleaving filter with polarization-controlled free spectral range

Here we propose an optical fiber interleaving filter based on a polarization-diversified loop (PDL), which can offer a polarization-controlled free spectral range (FSR). The proposed filter consists of a four port polarization beam splitter, two polarization-maintaining fiber (PMF) segments with equal birefringence (B) and different lengths (L and 2L), three half-wave plates (HWPs), and a Faraday rotator. Basically, the PMF segments within the PDL create polarization interference as the birefringence elements of the proposed filter, and the filter can provide different interference comb spectra depending on input polarization due to non-reciprocal polarization rotation caused by a Faraday rotator. For two orthogonal input polarization states, comb spectra of different FSRs or an equal FSR can be obtained, including their interleaved spectra, by controlling the orientation angles (θh1, θh2, θh3) of the three HWPs. More specifically, in a specific set (Set I) of (θh1, θh2, θh3), the FSRs of S1 (∝ 1/BL) and S3 (∝ 1/3BL) can be obtained for input polarization states of linear horizontal polarization (LHP) and linear vertical polarization (LVP), respectively. By varying only θh2 in Set I, which results in a new angle set designated as Set II, S1 can be exchanged with S3. At another set of three HWP angles (, designated as Set III or IV), the comb spectrum of the filter has an FSR of S1 or S2 (∝ 1/2BL) for LHP input, respectively, and this comb spectrum at each set is shifted by half the interference period, i.e., interleaved, for LVP input. In particular, for these FSR switching functions realizable at Sets I-IV, an interleaved version of the two orthogonally polarized comb spectra in each set can be drawn out by adjusting only θh1 or θh3. What is more, in a reverse operation mode with the filter input swapped with its output, four types of filtering operation at Sets I-IV can be reproduced at different four sets (Sets V-VIII) of (θh1, θh2, θh3). This theoretical prediction on the filter operation was experimentally investigated by constructing the filter, and the abovementioned eight types of filtering operation (at Sets I-VIII) were successfully verified.

Compact dual‐polarized meandered dipole antenna with LC‐balun integrated CPW‐G feeding lines for UHF RFID applications

AbstractThis article presents a compact dual‐polarized meandered dipole antenna with an LC‐balun integrated coplanar waveguide with ground (CPW‐G) feeding lines for ultrahigh frequency radio frequency identification handheld readers. It consists of printed ±45° dipole antennas on an upper substrate with parasitic elements on a lower substrate, which is made by a fan‐shaped meandered line. The feeders for the radiators are independently made up of a CPW‐G line in supports and it is connected to the radiator by LC‐balun. The proposed antenna has vertical and horizontal linear polarization, and it is fabricated on an RF‐35 substrate and the size is 0.21 λ0× 0.21 λ0 × 0.08 λ0 at 915 MHz. The peak gain and 10‐dB impedance bandwidth are approximately 3.3 dBi and 12%, respectively. In addition, measured isolation between two radiators is approximately 32 dB at 915 MHz.