Continuous phase amplification with a Sagnac interferometer

TL;DR

This paper introduces a phase amplification method using a Sagnac interferometer inspired by weak value amplification, achieving linear phase signal variation and comparable sensitivity to balanced homodyne detection.

Contribution

It presents a novel weak value inspired phase amplification technique in a Sagnac interferometer, utilizing dark port measurements for enhanced phase sensitivity.

Findings

Signal varies linearly with phase

Achieves sensitivity similar to balanced homodyne detection

Demonstrates classical and inverse weak value amplification mechanisms

Abstract

We describe a weak value inspired phase amplification technique in a Sagnac interferometer. We monitor the relative phase between two paths of a slightly misaligned interferometer by measuring the average position of a split-Gaussian mode in the dark port. Although we monitor only the dark port, we show that the signal varies linearly with phase and that we can obtain similar sensitivity to balanced homodyne detection. We derive the source of the amplification both with classical wave optics and as an inverse weak value.