Stable Optical Phase Modulation with Micromirrors

TL;DR

This paper demonstrates a micromirror-based optical phase modulator with high stability and tunable resonant frequency, achieving full phase modulation depth through thermal noise and voltage control.

Contribution

It introduces a stable micromirror device for optical phase modulation with tunable resonance and full phase shift capabilities, advancing integrated photonics.

Findings

Micromirror exhibits interferometric stability dominated by thermal noise.

Full phase modulation of ±π achieved at 11V sinusoidal excitation.

Resonant frequency can be tuned via applied voltage.

Abstract

We measure the motional fluctuations of a micromechanical mirror using a Michelson interferometer, and demonstrate its interferometric stability. The position stability of the micromirror is dominated by the thermal mechanical noise of the structure. With this level of stability, we utilize the micromirror to realize an ideal optical phase modulator by simply reflecting light off the mirror and modulating its position. The resonant frequency of the modulator can be tuned by applying a voltage between the mirror and an underlying electrode. Full modulation depth of +/-\pi is achieved when the mirror resonantly excited with a sinusoidal voltage at an amplitude of 11V.