Waveguide Polarizer Research Articles

Design of millimeter wave broadband polarization reconfigurable horn antenna based on elliptical waveguide polarizer

AbstractA broadband polarized reconfigurable horn antenna for K‐band and Ka‐band is designed using a circular polarizer in the form of an elliptical waveguide and a circular waveguide flange based on a gap structure. The designed noncontact circular waveguide flange with gap structure can switch the antenna excitation signal to different modes of electromagnetic waves by mechanical rotation. When excited by different modes of electromagnetic waves, the designed elliptical waveguide circular polarizer can switch between linear polarization, left‐handed circular polarization, and right‐handed circular polarization. The antenna is analyzed in principle, modeled and simulated, and processed by three‐dimensional printing process. The measured results show that S11 ≤ −15dB, axial ratio ≤ 3 dB, gain ≥14 dBi in 37.8% relative bandwidth range (22.5–33 GHz). The proposed antenna is broadband, multipolar, and reconfigurable, which makes it have broad application prospects in the field of satellite communication and millimeter‐wave communication.

Effect of surface anchoring energy on a liquid crystal optical waveguide-based polarization rotator

This study reports the effect of the surface anchoring energy of a liquid crystal (LC) cell on the performance of the liquid crystal optical waveguide polarization rotator (LCOW-PR) for the purpose of providing a theoretical reference for practical preparation of the LCOW-PR. First, the expression for the deflection angle of the director at the boundary of the LC cell is derived so that the distributions of the director and dielectric tensor of the LC can be accurately solved under any anchoring energy. On this basis, the correlation between the crucial indicators such as the polarization conversion length (PCL) together with the polarization conversion efficiency (PCE) of the LCOW-PR and the anchoring effect strength is constructed by combining with the existing numerical algorithms. The numerical results show that the maximum variation of the PCL is lower than 0.1 µm as the anchoring effect strength increases from 1×10−6J/m2 to 1×10−3J/m2, while the PCE decreases from 99.72% to 78.33%. This implies that the PCL of the LCOW-PR does not depend on the surface anchoring energy, but the anchoring effect strength of the orientational layer must be controlled to the order of 10−6J/m2 or even lower to achieve high-performance conversion between the polarization modes. Simultaneously, the effectiveness of the calculations in this work is verified with the help of the coupled mode theory as well as a comparison to previous reports.

Chalcogenide TE-Pass Waveguide Polarizer and Polarization Beam Splitter Base on Asymmetric Directional Coupling

Chalcogenide TE-Pass Waveguide Polarizer and Polarization Beam Splitter Base on Asymmetric Directional Coupling

ÇİFT-BANT İRİS POLARİZÖR TASARIM VE OPTİMİZASYONU

The structure that transforms a linear polarized signal into right-hand or left-hand circularly polarized signals is called a polarizer. In this study, a dual-band waveguide polarizer used in satellite communications is presented. The waveguide polarizer is designed using iris structures on a square waveguide. The purpose of the polarizer is to transmit the ±45° tilted linearly polarized signal at its input to the output as a right-hand or left-hand circularly polarized wave, and vice versa. At the input of the polarizer, a transition is designed between the WR42 waveguide and the square waveguide. At the output stage, a transition from square waveguide to circular waveguide is designed. In this paper, the design steps of both the polarizer and the transition sections, the optimization parameters, and simulation results are presented in full detail. The simulations are performed with a commercial electromagnetic simulation software, CST Studio Suite. The design operates within the Ka-band, specifically at 17.2 – 21.2 GHz and 27.5 – 31 GHz frequency bands. The insertion loss of the iris polarizer is 23 dB, and the phase difference is less than 15° around 90° for both bands.

EXCITATION OF WAKE SURFACE PLASMON-PHONON OSCILLATIONS BY A RELATIVISTIC ELECTRON BUNCH IN A POLAR SEMICONDUCTOR WAVEGUIDE

The process of surface wakefields excitation by the relativistic electron bunch in a polar semiconductor waveguide with a vacuum channel for electron bunch propagation is studied. The spectra and spatio-temporal structure of the excited surface wakefield in such system are investigated. It is shown that the excited full surface wakefield in the terahertz and infrared frequency ranges consists of the fields of LF and HF hybrid plasmon-phonon oscillations. The amplitudes of them are determined.

Ultrawideband Dual Circularly Polarized Waveguide Array Antenna for K- and Ka-Bands Satellite Communications

In the letter, a wideband dual circularly polarized (CP) waveguide antenna array is designed for K and Ka dual-band satellite communications. A multi-stage square waveguide structure is exploited into the radiating part to facilitate the excitation of a dual polarization response. A ridge waveguide polarizer is integrated to form the left-hand circular polarization (LHCP) and the right-hand circular polarization (RHCP). For a better arrangement of the feeding network, a transition structure with E-plane waveguides to double-ridge waveguides reduces the cross-sectional area of the feeding network. An 8 x 8 array antenna prototype was designed, fabricated and measured for demonstration purposes. The axial ratio (AR) and impedance bandwidth of the array antenna are more than 45%, according to simulation and measurement results. Input reflection coefficient and isolation lower than -15 dB for the dual CP from 19 to 30 GHz, the total antenna efficiency for the entire operating band exceeded 72%. For both polarizations, the peak gain ranges between 24.6 and 28.8 dBi from 19 to 30 GHz.

Effects of Wave-Mean Flow Interaction on the Multi-Time-Scale Variability of the AO Indices: A Case Study of Winters 2007/08 and 2009/10

Wave-mean flow interaction is usually regarded as accounting for the origin of the Arctic Oscillation/Northern Hemisphere Annular Mode (AO/NAM). It is inferred that the combination of the local wave-mean flow interactions at the AO/NAM’s three regional centers of action on three important time scales contributes to the main behavior of the AO/NAM index. To discuss the variations of the AO/NAM indices on the three prominent time scales, we take the 2007/08 and 2009/10 winters as two comparative examples to analyze the local wave-mean flow interactions at the AO/NAM’s three centers. The following three facets are identified: (1) Synoptic-scale wave breakings in the North Atlantic can explain the variances of the AO/NAM index on a time scale of 10–20 days. In the 2007/08 winter, there were both cyclonic and anticyclonic synoptic wave breakings, while in the 2009/10 winter, cyclonic synoptic wave breaking was dominant, and the flow characteristics were strikingly similar to the blocking. (2) In the 2007/08 and 2009/10 winters, the signals of the AO/NAM indices on the time scale of 30–60 days are mainly from the interactions between the upward propagating quasi-stationary waves and the polar vortex in the stratosphere. (3) This work also demonstrates that the AO/NAM is linked to the El Niño–Southern Oscillation (ENSO) by the Pacific–North American pattern (PNA) on the winter mean time scale. In the 2007/08 (2009/10) winter, La Niña (El Niño) forced the Pacific jet to shift poleward (equatorward), in favor of weakening (enhancing) the polar waveguide; thus, the polar vortex became stronger (weaker), corresponding to the positive (negative) winter mean AO/NAM index.

Microstructure realization of a lattice-based polar solid for arbitrary elastic waveguiding

The ability to precisely directing and controlling longitudinal (P) and transverse (S) waves in 2D solids along an arbitrary trajectory has attracted significant research interest and is crucial for practical applications such as imaging, cloaking, and wave focusing. Here, we report, design and examine an inhomogeneous lattice-based polar medium for ideal elastic waveguide, whose microstructures are inversely determined by the discrete transformation elasticity (DTE). Microstructures of the suggested medium, which are realized through global linear transformation and local affine transformation, enables arbitrary waveguides to transport elastic waves with minimal energy loss. Numerical simulation is then conducted to demonstrate that the lattice-based polar waveguide can efficiently steer both in-plane P and S wave modes over a broad frequency band. We also leverage the medium for Rayleigh wave control on curved surfaces. The constructed polar surface can break the conventional limit of the Rayleigh wave propagation on both concave and convex surfaces with extreme curvatures. This study is not only a concrete manifestation of the polar material, discrete transform elasticity, and their advantages but also provides a great potential in engineering applications such as signal detection, vibration control, and earthquake protection.

An active straight waveguide polarization rotator in single crystal thin film barium titanate-on-insulator

Electro-optic materials play an essential role in telecommunications. In active devices like Mach–Zehnder modulators, typically the diagonal Pockels coefficients are employed to induce an optical phase shift through electrical tuning of the refractive index along an optic axis. On the other hand, waveguide polarization rotators are usually passive devices where asymmetric structures or specially designed couplers are used. In this Letter, we exploit off diagonal Pockels coefficients to demonstrate an active straight waveguide polarization rotator using a c-axis single crystal thin film barium titanate (BTO)-on-insulator, with a maximum power conversion of ∼30% from the input TE (or TM) mode into its orthogonal mode observed. The device is switched on or off through an applied voltage and is demonstrated in a simple straight waveguide. A TM output extinction ratio of 26.1 dB is achieved in the device with a TE input. The r51 value in the BTO thin film is estimated to be around 600 pm/V. This work adds a different polarization rotation scheme to the active photonics family.

Stepped-height ridge waveguide MQW polarization mode converter monolithically integrated with sidewall grating DFB laser.

We report, to the best of our knowledge, the first demonstration of a 1555-nm stepped-height ridge waveguide polarization mode converter monolithically integrated with a sidewall grating distributed-feedback (DFB) laser using the identical epitaxial layer scheme. The device shows stable single longitudinal mode (SLM) operation with the output light converted from TE to TM polarization with an efficiency of >94% over a wide range of DFB injection currents (IDFB) from 140 mA to 190 mA. The highest TM mode purity of 98.2% was obtained at IDFB = 180 mA. A particular advantage of this device is that only a single step of metalorganic vapor-phase epitaxy and two steps of III-V material dry etching are required for the whole integrated device fabrication, significantly reducing complexity and cost.

Compact Shared-Aperture Dual-Band Dual-Circularly-Polarized Waveguide Antenna Array Operating at K/Ka-Band

In this article, a compact shared-aperture dual-band dual-circularly polarized waveguide antenna array is presented to achieve high gain and wide bandwidth in full-duplex satellite communication at K/Ka-band. The designed antenna array can simultaneously operate at 20 GHz band with right-hand circular polarization (RHCP) radiation and 30 GHz band with left-hand circular polarization (LHCP) radiation. The array is composed of circular polarization (CP) waveguide antenna elements and full-corporate feed networks. The ridged spectrum polarizer is inserted in the square waveguide to form CP radiation in a stepped waveguide antenna element. The sequential rotation technique is adopted in feed networks to further improve CP axial ratio (AR) performance and bandwidth. The prototype of the proposed 4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times4$ </tex-math></inline-formula> antenna array is fabricated and measured for demonstration. Experimental results show that the overlapped bandwidth in terms of reflection coefficients less than −10 dB and AR lower than 2 dB is 18–22 GHz for RHCP radiation in K-band, and the corresponding bandwidth for LHCP radiation in Ka-band is 28–32 GHz. The measured cross-polarization levels are better than 25.82 dB at 20 GHz and 20.25 dB at 30 GHz, and the measured peak gains at K/Ka-band are 23.94 and 26.87 dBic, respectively.

Three-Stepped Septum Waveguide Polarizer in the Operating Frequency Band 7.7-8.1 GHz

Three-Stepped Septum Waveguide Polarizer in the Operating Frequency Band 7.7-8.1 GHz

Compact Mid‐Infrared Chalcogenide Glass Photonic Devices Based on Robust‐Inverse Design

AbstractMid‐infrared (mid‐IR) on‐chip photonic devices have attracted increasing attention because of their potential applications in chemical and biological sensing and optical communications. In particular, chalcogenide glasses (ChGs) have long been regarded as promising materials for mid‐IR integrated photonics, owing to their broad infrared transparency, high nonlinearity, and excellent processing capabilities. Here, an inverse design approach is introduced to ChG photonic device design with a new robust inverse design method. A high‐performance mid‐IR inverse design polarization beam splitter, waveguide polarizer, mode converter, and wavelength demultiplexer are demonstrated for the first time. They all have a footprint of only several micrometers. The robust inverse design method could improve the robustness of device performance against fabrication variations and would be a general approach for designing and optimizing miniaturized chalcogenide photonic devices.

Dual-Circularly Polarized Array Antenna Based on Gap Waveguide Utilizing Double-Grooved Circular Waveguide Polarizer

This article presents a dual-circularly polarized array antenna based on gap waveguide technology operating at E-band. Double-grooved circular waveguide polarizers that utilize two annulus grooves placed at 45° and 135° offset from both excitation ports are used in this work. The operating principles of the polarizer are analyzed. Multilayer design using gap waveguide is implemented on the basis of the polarizer. The antenna consists of six layers, including three layers for the feeding networks, one layer for the polarizer, one layer of back cavity, and another layer of radiating grid. A 2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 2 unit cell is proposed first and employed to realize an 8 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 8 planar array. Corporate feeding networks that use compact E-plane T-junctions and H-plane T-junctions are proposed. The antenna has been fabricated and verified by measurements. The measured results of S-parameters agree well with the simulation and show that reflection coefficients are better than −10 dB for both circular polarizations (CPs) from 76 to 81 GHz. The measured isolation between the input ports is larger than 25 dB in the operating band. The far-field measurements show that the antenna has realized gain larger than 24 dBi and axial ratios less than 1.5 dB from 76 to 81 GHz at boresight direction.

Compact TE-pass polarizer based on lithium-niobate-on-insulator assisted by indium tin oxide and silicon nitride

An indium tin oxide (ITO) and silicon nitride (Si3N4) assisted compact TE-pass waveguide polarizer based on lithium-niobate-on-insulator is proposed and numerically analyzed. By properly designing the ITO and Si3N4 assisted structure and utilizing the epsilon-near-zero effect of ITO, the TM mode is strongly confined in the ITO layer with extremely high loss, while the TE mode is hardly affected and passes through the waveguide with low loss. The simulation results show that the polarizer has an extinction ratio of 22.5 dB and an insertion loss of 0.8 dB at the wavelength of 1.55 μm, and has an operating bandwidth of about 125 nm (from 1540 nm to 1665 nm) for an extinction ratio of > 20 dB and an insertion loss of < 0.95 dB. Moreover, the proposed device exhibits large fabrication tolerances. More notably, the device is compact, with a length of only 7.5 μm, and is appropriate for on-chip applications.

Electromagnetic Performance of Waveguide Polarizers with Sizes Obtained by Single-Mode Technique and by Trust Region Optimization

Modern wireless networks, stationary terrestrial and satellite systems use many modern technologies to increase communication channels information capacity. They save limited frequency resources. In satellite communications the polarization signal processing is applied to reuse the allocated frequency bands. Usage of circularly polarized electromagnetic waves, which transmit useful signals, reduces fading effects and eliminates disadvantages introduced by multipath propagation interferences. In this case the distortion levels for signals with an odd number of electromagnetic waves reflections in the receiving antenna systems will be reduced down to the thresholds of their cross-polarization isolation. Besides, in the case of orthogonal polarizations usage, the achieved information capacity of the applied wireless communication channel multiples almost by the factor of two. The type of polarization of the used electromagnetic wave strongly determinates the peculiarities of the process of its propagation in the space or transmission line. Polarization signal processing is frequently carried out in horn feed systems of the reflector antennas. Such feed networks and systems allow to transmit and receive signals with several kinds of polarization at the same time. The fundamental element of dual circular polarization antenna feed networks is a waveguide polarization duplexer. The phase, isolation and matching characteristics of a polarization converter strongly influence on the functionality and polarization discrimination possibilities of the entire reflector antenna system. Therefore, the development and optimization of the characteristics of waveguide polarizers for satellite communication antennas is a crucial technical problem, which must be solved by fast and accurate methods. The comparison of electromagnetic performance of waveguide polarizers with sizes obtained using a fast single-mode technique and by more accurate trust region optimization method is carried out in this research. The results for differential phase shift, level of voltage standing wave ratio, ellipticity coefficient and cross-polarization discrimination are shown and discussed.

Polarization-Dependent Scattering of Nanogratings in Femtosecond Laser Photowritten Waveguides in Fused Silica.

The properties of polarization-selective, light-guiding systems upon subwavelength nanogratings formation in the case of type II refractive index traces induced by femtosecond laser pulses in bulk fused silica were studied. Polarization-dependent scattering is analyzed both in simulation using a finite-difference, time-domain method and in experiments. We argue that the polarization-sensitive optical guiding of type II waveguides is due to polarization-dependent scattering of nanogratings. Optical designs can then be suggested where the guiding efficiency of type I traces can be combined with type II anisotropies. A low-loss waveguide polarizer is demonstrated based on the modulation of the evanescent field emerging from type I waveguides using polarization-dependent scattering of neighboring nanogratings.

Accuracy and Agreement of FDTD, FEM and Wave Matrix Methods for the Electromagnetic Simulation of Waveguide Polarizers

Waveguide devices of polarization processing are key elements of modern dual-polarized antenna systems. Such antenna systems carry out polarization transformation and separation of signals with orthogonal polarizations in satellite communications and radar appliances. Well-known electrodynamic methods are used to simulate performance of such devices. This paper investigates the accuracy and mutual matching of wave matrix method with FDTD and FEM. The wave matrix method is based on the theory of scattering and transmission matrices. The main electromagnetic characteristics of a polarizer were obtained through the elements of these matrices. The main characteristics of a polarizer were compared. They include phase difference of orthogonal polarizations, level of voltage standing wave, ellipticity coefficient and level of cross-polarization isolation. Comparison of electromagnetic characteristics was carried out at the example of a waveguide iris polarizer for the operating frequency range from 13.0 to 14.4 GHz. In addition, the process of optimization of electromagnetic characteristics was carried out by changing the geometric dimensions of a polarizer. Calculated by different theoretical methods characteristics were compared and analyzed. Results, which were obtained by considered methods, are in good agreement

EXCITATION OF WAKE FIELDS BY A RELATIVISTIC ELECTRON BUNCH IN A POLAR SEMICONDUCTOR WAVEGUIDE

The process of wake fields excitation by a relativistic electron bunch in polar semiconductors is studied. Cylindrical semiconductor waveguide, in which relativistic electron bunch moves along axis, is considered. It is shown that the excited wake field in the terahertz and infrared frequency ranges consists of the field of longitudinal HF and LF hybrid plasmon-phonon oscillations and the field of the HF and LF transverse polaritons, which are a set of eigen electromagnetic waves of the polar semiconductor waveguide. The spatio-temporal structure of the total excited wake field is obtained, the intensity of the excited wake waves is determined.

Microwave waveguide polarizer for satellite communication antennas with circular polarization

The volumes of information transmitted in modern satellite telecommunication systems are constantly increasing. Antennas with signal polarization processing, which is performed by polarizers, are the fundamental elements of such systems. Therefore, the development of methods for the analysis of new polarizers is an important problem. From a technological point of view, polarizers based on waveguides with irises are the simplest. Analysis and optimization of electromagnetic characteristics of a polarizer based on a square waveguide with irises are the goals of the presented research. To solve this optimization problem, we have created a new mathematical model, which allows investigating the influence of the design parameters of the polarizer on its electromagnetic characteristics. A mathematical model of the waveguide polarizer with irises was created by the method of decomposition using wave transmission and scattering matrices. Besides, the new mathematical model takes into account the thickness of the irises using their equivalent T- and П-shaped substitution circuits. The general wave scattering matrix is the basis of a new mathematical model of a waveguide polarizer. This matrix was determined using the theory of microwave circuits. The main characteristics of the waveguide polarizer were determined through the elements of this matrix. Here, we perform the optimization of the polarizer characteristics in the Ku-band 10.7–12.8 GHz. The developed new mathematical model of a waveguide polarizer with irises makes it possible to take into account the heights of the irises, distances between them and their thickness. The new mathematical model determines the electromagnetic characteristics of the polarizer in a simpler and faster way compared to the finite integration technique, which is often used for the analysis of microwave devices for various purposes