A Translational Polarization Rotator

TL;DR

This paper presents a novel free-space polarization modulator that uses a variable phase delay between circular polarization components to rotate linear polarization, demonstrated at microwave frequencies with a prototype device.

Contribution

The paper introduces a new polarization modulation device based on a movable mirror and circular polarizer, enabling controlled polarization rotation in free space.

Findings

Modulates Stokes Q and U over a 20% bandwidth from 77 to 94 GHz.

Demonstrates a prototype device with effective polarization control.

Achieves polarization rotation proportional to phase delay.

Abstract

We explore a free-space polarization modulator in which a variable phase introduction between right- and left-handed circular polarization components is used to rotate the linear polarization of the outgoing beam relative to that of the incoming beam. In this device, the polarization states are separated by a circular polarizer that consists of a quarter-wave plate in combination with a wire grid. A movable mirror is positioned behind and parallel to the circular polarizer. As the polarizer-mirror distance is separated, an incident linear polarization will be rotated through an angle that is proportional to the introduced phase delay. We demonstrate a prototype device that modulates Stokes Q and U over a 20% bandwidth, from 77 to 94 GHz.