Omnidirectional Polarization Research Articles

An ultra-thin optical polarizer based on weyl semimetals

Recently, Weyl semimetals have been extensively studied due to their unique optical responses, especially in the mid-infrared region. However, the possibility of developing optical polarizers based on Weyl semimetals remains unexplored. In this paper, under the Voigt geometry, we numerically show that an ultra-thin Weyl semimetal film with thickness L = 100 nm can achieve an impressive polarization extinction ratio (more than 40 dB) with a wide acceptance angle. Further, the proposed sandwich structure can effectively adjust the position of the TE mode transmission peak alone, thus obtaining lower insertion loss (from 0.06 dB to 0.03 dB) and wider acceptance range of angle (from 49.5∘ to 71∘). The proposed gradient Fermi level structure eliminates the Fabry-Perot cavity resonance, thus resulting a wider bandwidth (approximately 60 % improvement). Our proposed ultra-thin and wide-angle polarizer may have potential applications in optical communication and omnidirectional polarization detectors.

Low Profile Dual-Band Polarization Conversion Metasurface with Omnidirectional Polarization.

In this work, a dual-band transmissive polarization conversion metasurface (PCM), with omnidirectional polarization and low profile, is proposed. The periodic unit of the PCM is composed of three metal layers separated by two substrates. The upper patch layer of the metasurface is the patch-receiving antenna, while the bottom layer is the patch-transmitting antenna. Both antennas are arranged in an orthogonal way so that the cross-polarization conversion can be realized. The equivalent circuit analysis, structure design, and experimental demonstration are conducted in detail, the polarization conversion rate (PCR) is greater than 90% within two frequency bands of 4.58-4.69 GHz and 5.33-5.41 GHz, and the PCR at two center operating frequencies of 4.64 GHz and 5.37 GHz is as high as 95%, with a thickness of only 0.062λL, where λL is the free space wavelength at the lowest operating frequency. The PCM can realize a cross-polarization conversion, when the incident linearly polarized wave at an arbitrary polarization azimuth, which indicates that it has the characteristics of omnidirectional polarization.

Angle of polarization calibration for omnidirectional polarization cameras.

Polarization cameras quantify one of the fundamental properties of light and capture intrinsic properties of the imaged environment that are otherwise omitted by color sensors. Many polarization applications, such as underwater geolocalization and sky-based polarization compass, require simultaneous imaging of the entire radial optical field with omnidirectional lenses. However, the reconstructed angle of polarization captured with omnidirectional lenses has a radial offset due to redirection of the light rays within these lenses. In this paper, we describe a calibration method for correcting angle of polarization images captured with omnidirectional lenses. Our calibration method reduces the variance of reconstructed angle of polarization from 76.2 ∘ to 4.1 ∘. Example images collected both on an optical bench and in nature, demonstrate the improved accuracy of the reconstructed angle of polarization with our calibration method. The improved accuracy in the angle of polarization images will aid the development of polarization-based applications with omnidirectional lenses.

Comparison of omnidirectional reflectivity of quasi-periodic dielectric multilayers

Optical reflectivity properties of various dielectric multilayer sequences of thin films are investigated. Wavelength, incident angle, TE, TM polarization parameters are changed and omnidirectional polarization and wavelength independent highly reflective structures are researched. In this research 1D periodic, Fibonacci, Thue–Morse, double-period and Rudin–Shapiro sequences are considered. It is found that the perfect reflective structure can be obtained with single period Rudin–Shapiro structure with a high order.

Design of Double Cross Dipole Antenna as NOAA Satellite Signal Receiver for Monitor Cloud Conditions Application

NOAA is a remote sensing satellite that contains informations about the earth, such as mapping land, sea and reporting weater conditions, cloud conditions and hotspots in an area. NOAA satellite works at the downlink frequency of 137-138 MHz. Double Cross Dipole antenna can be used as signal receiver antenna from NOAA satellite. Double cross dipole antenna is design to operate at frequency range of 137-138 MHz. simulation result of 137.62 MHz frequency generate return of loss as -20.726 dB, the value of VSWR 1.20 bandwidth of 82.32 Mhz, omnidirectional polarization and circular polarization. The result of measurement of double cross dipole antenna it was obtained return loss as-18.911 dB, value of VSWR of 1.255, bandwidth of 32.813 MHz. Double cross dipole antenna can be used to receive NOAA satellite signal in a form of voice. Voice data can be converted into image with the help of WXtoImgsoftware. The result of conversion was in a form of cloud condition in Indonesia area.

Omnidirectional polarization beam splitter for white light.

As a key element in optical systems, a broadband and omnidirectional polarization beam splitter has been long desired. Here, based on anisotropic metamaterials, a perfect polarizing beam splitter is theoretically designed for the extremely broad frequency and angle bands without energy loss. When an electromagnetic wave is incident on the beam splitter, the transverse magnetic-polarized component suffers total reflection, while the transverse electric-polarized component is completely transmitted within the incident angle range [-90°, 90°] for the white light. This study provides a new approach to design an efficient polarizing beam splitter and may promote the development and applications of anisotropic metamaterials.

Arbitrarily Directional and Tunable Polarization Rotating Effect with Coupled Metal Screens

Active polarization rotators are desirable for many applications in photonics. Metasurfaces based on phase-change or magneto-optical materials can do the job, but suffer from long response time or the need for a strong magnetic field. This study reports tunable and omnidirectional polarization rotation using a pair of coupled, perforated metal screens. Here the tuning originates from the near-field coupling of the screens and its dependence on lateral displacement. For millimeter-scale displacement, continuous and efficient polarization rotation from -90 to 90 degrees can be achieved in the microwave band, and the effect could also be extended to the terahertz regime.

An Omnidirectional Polarization Detector Based on a Metamaterial Absorber.

The theory, design, simulation, fabrication, and performance of an omnidirectional polarization detector (PD) with two resonances located in the X and Ka ranges based on a metamaterial absorber (MMA) are presented in this paper. The sandwich structure of PD is composed of 0.1 μm periodic “I” shaped patches on the metasurface, a dielectric of 200 μm FR-4 on the interlayer, and a 0.3 μm copper film on the substrate. PD absorptivity is first used to reflect and describe the polarization of the incident wave. The numerical results, derived from the standard full wave finite integration technology (FIT) of CST 2015, indicates that the designed PD shows polarization sensitivity at all incidence angles. The effects on absorptivity produced by the incidence angles, polarization angles, and materials are investigated. The amplitude of absorptivity change caused by polarization reaches 99.802%. A laser ablation process is adopted to prepare the designed PD on a FR-4 board coated with copper on the double plane with a thickness that was 1/93 and 1/48 of wavelength at a resonance frequency of 16.055 GHz and 30.9 GHz, respectively. The sample test results verify the designed PD excellent detectability on the polarization of the incident waves. The proposed PD, which greatly enriches the applications of metamaterials in bolometers, thermal images, stealth materials, microstructure measurements, and electromagnetic devices, is easy to mass produce and market because of its strong detectability, ultrathin thickness, effective cost, and convenient process.

Helicity‐Preserving Omnidirectional Plasmonic Mirror

A helicity preserving near-infrared mirror with a reflection efficiency over 91% for incidence angles up to 60° on any arbitrary incidence plane is realized by establishing a unified design framework of artificial electromagnetic boundaries of metasurfaces for omnidirectional polarization control. Similar efficiency and angular range of operation are observed for cross-linear polarization conversion as well.

Omnidirectional polarization-insensitive tunable absorption in graphene metamaterial of nanodisk structure

Tunable absorption based on graphene metamaterial with nanodisk structure at near-infrared frequency was investigated using the finite difference time domain method. The absorption of the nanodisk structure which consisting of Au-MgF2-graphene-Au-polyimide (from bottom to top) can be tuned by the chemical potential of graphene at certain diameter of nanodisk. The permittivity of graphene is discussed with different chemical potential to obtain tunable absorption. It is shown that the increased value of the chemical potential of graphene can lead to blue-shifted of the absorption peaks and the values decreased. Moreover, dual-band and triple-band absorption can be achieved for resonance frequencies at normal incidence. Compared with diameter of nanodisks, the multilayer structure shows multi-band absorber, and an omnidirectional absorption at 195.25 THz is insensitive to TE/TM polarization. This omnidirectional polarization insensitive absorption may be applied by optical communications such as optical absorber, near infrared stealth, and filter.

Design of wide-angle and broad-band two-dimensional photonic crystal polarization splitter by the automatic shaping mechanism

Based on the mechanism of automatic shaping, the corrugated multilayer films of two_dimensional (2D) phtonic crystal is designed.This structure realizes omnidirectional polarization splitting with TM mode passing window between λ＝148 and 152μm, which is the complete band gap of TE mode. The variable rang es of the slope angle of the layers and the width of a-Si single layer are 38° —49° and 014—015μm, respectively. Band structure has been used to expl ain the omnidirectional polarization effect. An arrow-end_like 2D photonic cryst al which is the deformation of the corrugated multilayer films is introduced for comparison. It can only work as a wide-angle polarization splitter not as an o mnidirectional one for wavelength from 128 to 131μm. The comparison of th e band structures of these two different 2D photonic crystals leads to the metho d of extending the incident angle of polarization splitter.