Single-Element Dual-Interferometer for Precision Inertial Sensing: Sub-picometer Structural Stability and Performance as a Reference for Laser Frequency Stabilization

TL;DR

This paper presents a compact monolithic Mach-Zehnder interferometer achieving sub-picometer stability, enabling ultra-precise laser frequency stabilization crucial for high-sensitivity inertial sensing in the millihertz range.

Contribution

The work introduces a novel, highly stable interferometer design that significantly improves laser frequency stabilization performance for precision inertial measurements.

Findings

Achieved fractional frequency instability better than 6×10^{-13}

Interferometer pathlength stability better than 10^{-12} m/√Hz

Demonstrated suitability for sub-picometer inertial sensing

Abstract

To reach sub-picometer sensitivity in the millihertz range, displacement sensors based on laser interferometry require suppression of laser-frequency noise by several orders of magnitude. Many optical frequency stabilization methods exist with varying levels of complexity, size, and performance. In this paper, we describe the performance of a compact Mach-Zehnder interferometer based on a monolithic optic. The setup consists of a commercial fiber injector, a custom-designed pentaprism used to split and recombine the laser beam, and two photoreceivers placed at the complementary output ports of the interferometer. The structural stability of the prism is transferred to the laser frequency via amplification, integration, and feedback of the balanced-detection signal, achieving a fractional frequency instability better than 6 parts in $10^{13}$, corresponding to an interferometer pathlength stability better than $10^{-12}$ m$/\sqrt{\mathrm{Hz}}$.