A monolithic interferometer for high-sensitive strictly-local detection of orbital angular momentum states of light

TL;DR

This paper introduces a stable, monolithic interferometer that can detect the topological charge of light's orbital angular momentum by analyzing only a small wavefront portion, effective even at the photon counting level.

Contribution

It presents a novel, stable monolithic birefringent crystal interferometer capable of local detection of orbital angular momentum states without feedback or thermal compensation.

Findings

Successfully distinguishes topological charge with minimal wavefront access

Operates effectively at the photon counting regime

Demonstrates stability and practicality of the monolithic design

Abstract

We propose an innovative monolithic interferometer to distinguish the topological charge of radiation carrying orbital angular momentum. Remarkably, our method requires to access only a small portion of the entire wavefront. The proposed scheme relies on a monolithic birefringent crystal, and as such it is intrinsically stable and does not require any feedback or thermal drift compensation. An experimental setup has been realized to prove the effectiveness of the proposed method down to the photon counting regime.