Polarization Properties of A Multi-Moded Concentrator

TL;DR

This paper introduces a non-imaging concentrator designed for broad-band polarimetry at millimeter to submillimeter wavelengths, demonstrating high polarization efficiency and stable beam patterns across frequencies.

Contribution

It presents a novel rectangular multi-moded concentrator design that preserves polarization and matches theoretical models with experimental measurements.

Findings

Co-polar beam pattern is frequency-independent.

Polarization efficiency is approximately 94%.

Cross-polar response is -18 dB after correction.

Abstract

We present the design and performance of a non-imaging concentrator for use in broad-band polarimetry at millimeter through submillimeter wavelengths. A rectangular geometry preserves the input polarization state as the concentrator couples f/2 incident optics to a 2 pi sr detector. Measurements of the co-polar and cross-polar beams in both the few-mode and highly over-moded limits agree with a simple model based on mode truncation. The measured co-polar beam pattern is nearly independent of frequency in both linear polarizations. The cross-polar beam pattern is dominated by a uniform term corresponding to polarization efficiency 94%. After correcting for efficiency, the remaining cross-polar response is -18 dB.