Adaptive Optics-Enhanced Michelson Interferometer for Spectroscopy of Narrow-Band Light Sources

TL;DR

This paper introduces a novel adaptive optics-enhanced Michelson interferometer with a spatial light modulator for fast, high-resolution spectroscopy of narrow-band light sources, enabling simple imaging-based spectral analysis.

Contribution

It demonstrates the use of a Michelson interferometer combined with adaptive optics and SLM for single-snapshot and multi-step spectroscopy, revealing inherent spectral fringe shifts and their applications.

Findings

Fringe shifts are wavelength-dependent and form a 'teardrop' pattern.

Adaptive optics allows spectroscopy without moving parts.

Single-snapshot spectroscopy is feasible with fringe pattern analysis.

Abstract

Adaptive optics enables the deployment of interferometer-based spectroscopy without the need for moving parts necessary for scanning the interferometer arms. Here, we employ a Michelson Interferometer in conjunction with a Spatial Light Modulator (SLM) for determining the spectral profile of a narrow-band light source. Interestingly, we observe that the fringes across the interferometer output beam are inherently shifted in wavelength even when a constant phase profile is provided to the SLM. We calibrate the spectral shifts as a function of fringe spatial location by measuring the incident light spectrum at various points across the fringe pattern, and observe that the spectral peak traces out a `teardrop' shape, whose width is dependent on the spectral bandwidth of the source, the relative tilt and path difference between the two arms of the interferometer, and the divergence of the beam. Next, we demonstrate that this inherent spectral variation of the fringes can be used to perform fast single-snapshot spectroscopy of narrow-band light sources, while a time-varied phase profile provided to the SLM leads to multi-step spectroscopy with lower noise, higher resolution, and better contrast. Our findings establish that the Michelson Interferometer can be used to perform spectroscopy of any source within a certain spectral range from simple images of the fringe pattern, so as to facilitate exciting applications towards hyperspectral imaging.