Analysis of throughput for multilayer infrared meanderline waveplates

Abstract

A meanderline wave retarder is a unique type of frequency-selective-surface (FSS) that enables a change in the state of optical polarization. The principles of operation are very similar to a typical crystalline waveplate, such that the artificially structured meanderline array has both 'slow' and 'fast' axes that provide a phase offset between two orthogonal wave components. In this paper, we study the behavior and response of multilayered meanderline quarter-wave retarders designed for operation at 10.6 mum wavelength (28.28 THz). It will be shown that meanderline quarter-wave plates with more than a single layer exhibit improved transmission throughput at infrared frequencies due to impedance matching, similar to a multilayer optical film coating. Numerical data, both from simulations and measurements, are presented to validate this claim.

Ultrathin Terahertz Quarter-wave plate based on Split Ring Resonator and Wire Grating hybrid Metasurface

“…The transmission characteristics of the metasurface can be conveniently described by representing the metasurface as lumped impedance connected to a transmission line. This approach is commonly used for analyzing the metasurface response at microwave as well as THz frequencies2021. Figure 1 shows a schematic diagram of the metasurface and its equivalent circuit models under y and x-polarized incident fields.…”

Comparison of quarter-wave retarders over finite spectral and angular bandwidths for infrared polarimetric-imaging applications

“…1(b)) selected for this study represents a field of technology that has not yet been thoroughly investigated with regard to IR polarimetric-imaging. This device is the same 2-layer QWP component that was presented in [12], which is expected to exhibit achromatic polarimetric characteristics and angle-insensitive behavior, based upon past performance [12][13][14][15]. Multilayer meanderline QWPs have technological potential that could be employed in thermal IR po-larimeters, especially considering that they can be fabricated into a compact planar form factor that facilitates integration with other polarization devices and pixelated IR sensors.…”

“…A. Woollam Corp.) over the 8-12 μm band. These parameters include δ, the differential phase shift, and ψ, the auxiliary angle, which determine the axial ratio (AR), defined as the ratio between the major and minor axes of the transmitted polarization ellipse [2,12,13]…”

“…The increase in beam ellipticity is particularly due to the disparity between the surface impedance discontinuities of the TE and TM modes of the meanderline structure, which is intrinsically anisotropic due to the geometrical configuration of the metallic scatterers (see Fig. 1(b)) [12][13][14][15]. Secondly, the phase shift of the meanderline QWP exhibits two noticeable dips in its spectrum that signify further departure from ideal behavior.…”

“…7, we can observe a distinct difference between the form-birefringent and meanderline QWP technologies. The limiting factor that was hindering the form-birefringent structure, the Fresnel loss at the uncoated back side of the Si substrate, is now removed with the assistance of a BBAR coating [12,23]. Thus, the only scattering losses are those at the initial grating interface, which is highly transmissive because of its own antireflection-like effective medium properties [7,[16][17][18].…”