Control of Structured Light Enables Nearly Perfect Noise-filtering

TL;DR

This paper introduces a novel noise-filtering technique for laser-based sensing by controlling orbital angular momentum (OAM), enabling nearly perfect noise suppression even when signal and noise share similar properties.

Contribution

The study demonstrates, through experiments, that manipulating OAM can effectively distinguish signal from noise, surpassing traditional filtering methods.

Findings

OAM control improves signal-to-noise ratio significantly.

Azimuthal index and detection aperture influence filtering effectiveness.

OAM-based filtering is effective in high-noise environments.

Abstract

The performance of laser-based active sensing has been severely limited by two types of noise: electrical noise, stemming from elements; optical noise, laser jamming from an eavesdropper and background from environment. Conventional methods to filter optical noise take advantage of the differences between signal and noise in time, wavelength, and polarization. However, they may be limited when the noise and signal share the same information on these degrees of freedoms (DoFs). In order to overcome this drawback, we experimentally demonstrate a groundbreaking noise-filtering method by controlling orbital angular momentum (OAM) to distinguish signal from noise. We provide a proof-of-principle experiment and discuss the dependence of azimuthal index of OAM and detection aperture on signal-to-noise ratio (SNR). Our results suggest that using OAM against noise is an efficient method, offering a new route to optical sensing immersed in high-level noise.