Dispersion Control in Micromechanical Evanescent Optical Modulators

TL;DR

This paper introduces evanescent MEMS optical modulators that can control wavelength dispersion in novel ways, enabling advanced on-chip photonic functionalities.

Contribution

The work demonstrates experimentally and theoretically that evanescent MEMS modulators can achieve anomalous dispersion control, a capability not accessible with other modulator types.

Findings

Evanescent MEMS modulators exhibit negative group index change despite positive effective index modulation.

A novel MEMS actuator design enables these unique dispersion control capabilities.

Potential applications include broadband switching, photonic time delay, and nonlinear phase matching.

Abstract

Efficient, low-loss, and versatile optical modulators are a critical ingredient for practical integrated photonic systems. Modulators based on micro-electromechanical systems (MEMS) have unique advantages over more traditional thermal, electro-optic, or plasma dispersion modulators. In this work, we show that evanescent MEMS modulators (in which a dielectric slab is mechanically inserted into a waveguide's evanescent field) can exhibit anomalously dispersive modulation. That is, despite positive modulation of a waveguide mode's effective index, the modulator brings about a negative change in group index. We experimentally demonstrate these unique capabilities using a novel MEMS actuator design. The new theory and results here reveal that evanescent MEMS modulators possess a capability for control of wavelength dispersion not accessible to nearly any other type of modulator. These new capabilities may enable on-chip integration of systems for various optical applications, including broadband switching, photonic true time delay, pulse shaping, or phase matching of nonlinear processes.