Spatial optical mode demultiplexing as a practical tool for optimal transverse distance estimation

TL;DR

This paper demonstrates a practical method for estimating transverse distances between incoherent optical beams using spatial mode demultiplexing, achieving super-resolution beyond the Rayleigh limit with calibrated measurements.

Contribution

It introduces an experimental approach for spatial mode demultiplexing as a tool for precise transverse distance estimation, validated by theoretical and experimental agreement.

Findings

Achieved super-resolution distance measurements beyond Rayleigh limit.

Demonstrated accurate distance estimation in two dimensions with proper calibration.

Identified cross-talk as a sensitivity limit in the measurement process.

Abstract

We present the experimental implementation of simultaneous spatial multimode demultiplexing as a distance measurement tool. We first show a simple and intuitive derivation of the Fisher information in the presence of Poissonian noise. We then estimate the distance between two incoherent beams in both directions of the transverse plane, and find a perfect accordance with theoretical prediction, given a proper calibration of the demultiplexer. We find that, even though sensitivity is limited by the cross-talks between channels, we can perform measurements in 2 dimensions much beyond Rayleigh limit with a large dynamic.