Invariance of waveguide grating mirrors to lateral displacement phase shifts

TL;DR

This paper demonstrates that waveguide grating mirrors are highly insensitive to lateral displacement phase shifts, making them suitable for high-precision interferometry with relaxed alignment constraints.

Contribution

The study introduces a finite-difference time-domain simulation method to analyze lateral displacement coupling in WGMs, showing negligible phase noise coupling.

Findings

WGMs do not couple lateral displacements into reflected phase to 10^{-7} rad

WGMs are less sensitive to alignment errors than diffraction gratings

Phase noise from lateral shifts is negligible for WGMs

Abstract

We present a method to analyse the coupling of lateral displacements in nanoscale structures, in particular waveguide grating mirrors (WGM), into the phase of a reflected Gaussian beam using a finite-difference time-domain simulation. Such phase noise is of interest for using WGMs in high-precision interferometry. We show that WGMs do not couple lateral displacements into the phase of a reflected beam to a precision of 10^{-7} rad and that WGMs are therefore not subject to the same stringent alignment requirements as previously proposed layouts using diffraction gratings.