Fast, high-precision optical polarization synthesizer for ultracold-atom experiments

TL;DR

This paper introduces a high-precision optical polarization synthesizer capable of rapidly generating arbitrary polarization states with minimal depolarization, demonstrated through ultracold-atom experiments in polarization-controlled optical lattices.

Contribution

A novel polarization synthesizer method controlling phase and amplitude of superimposed laser fields, achieving near-perfect polarization purity and rapid modulation for ultracold-atom applications.

Findings

Achieved 99.99% polarization degree

Depolarization due to temporal fluctuations is two orders of magnitude smaller

Successfully demonstrated in ultracold-atom optical lattices

Abstract

We present a novel approach to precisely synthesize arbitrary polarization states of light with a high modulation bandwidth. Our approach consists of superimposing two laser light fields with the same wavelength, but with opposite circular polarizations, where the phase and the amplitude of each light field are individually controlled. We find that the polarization-synthesized beam reaches a degree of polarization of 99.99%, which is mainly limited by static spatial variations of the polarization state over the beam profile. We also find that the depolarization caused by temporal fluctuations of the polarization state is about 2 orders of magnitude smaller. In a recent work, Robens et al. [Phys. Rev. Lett. 118, 065302 (2017)] demonstrated an application of the polarization synthesizer to create two independently controllable optical lattices, which trap atoms depending on their internal spin state. We here use ultracold atoms in polarization-synthesized optical lattices to give an independent, in situ demonstration of the performance of the polarization synthesizer.