Enhanced interferometric resolution via N-fold intensity-product measurements without sacrificing phase sensitivity

TL;DR

This paper demonstrates experimentally that N-fold intensity-product measurements in an interferometer can enhance resolution without losing phase sensitivity, approaching shot-noise limit-like precision using classical light.

Contribution

It introduces and experimentally validates an N-fold intensity-product measurement method that improves resolution while maintaining phase sensitivity in optical interferometry.

Findings

Achieved resolution enhancement with N-fold intensity-product measurements.

Maintained phase sensitivity equivalent to the shot-noise limit.

Applicable to classical optical sensing platforms like fiber-optic gyroscopes.

Abstract

The Fisher information theory sets a fundamental bound on the minimum measurement error achievable from independent and identically distributed (i.i.d.) measurement events. The assumption of identical and independent distribution often implies a Gaussian distribution, as seen in classical scenarios like coin tossing and an optical system exhibiting Poisson statistics. In an interferometric optical sensing platform, this translates to a fundamental limit in phase sensitivity, known as the shot-noise limit (SNL), which cannot be surpassed without employing quantum techniques. Here, we, for the first time to the best of our knowledge, experimentally demonstrate a SNL-like feature on resolution of an unknown signal when intensity-product measurement technique is applied to N-divided MZI output subfields. Given the Poisson-distributed photon statistics, the N-divided subfields ensure the i.i.d. condition required by Fisher information theory. Thus, the N-fold intensity-product technique holds promise for enhancing the precision of conventional optical sensing platforms such as a fiber-optic gyroscope and wavelength meter, while preserving the original phase sensitivity of the output field.