High efficiency phase flattening based Laguerre-Gauss (LG) spectrometer using variable focus lenses

TL;DR

This paper introduces a high-efficiency, no-moving-parts LG spectrometer using variable focus lenses and a variable pinhole, significantly reducing losses and improving detection efficiency for LG mode spectra measurement.

Contribution

The paper presents a novel LG spectrometer design that overcomes classical phase flattening limitations with variable focus lenses, achieving near-zero coupling losses and mode-independent detection efficiency.

Findings

Coupling losses are nearly zero across modes.

Detection efficiency is maximized and mode-independent.

Losses can be pre-calibrated to correct efficiency bias.

Abstract

We propose a novel high-efficiency no-moving-parts Laguerre-Gauss (LG) spectrometer using two variable focus lenses and a variable sized pinhole that overcomes the limitations of the classical, projective, phase flattening technique for measuring the Laguerre-Gauss (LG) spectrum of light beams. Simulation results show that the coupling losses are virtually zero and the only losses are ring losses which are mode-dependent but beam waist-independent. Hence, the detection efficiency for all modes is simultaneously the maximum possible irrespective of the beam waist of the LG modes chosen for the decomposition. The losses can also be easily pre-calibrated to remove the efficiency bias amongst different modes.