Coupling of Light and Mechanics in a Photonic Crystal Waveguide

TL;DR

This paper reports on thermally driven vibrations in a photonic crystal waveguide and develops models to understand their impact on optical signals, aiming to enable quantum-level opto-mechanical interactions with atoms and photons.

Contribution

It introduces validated models for transducing mechanical vibrations into optical signals in a PCW designed for atom trapping, laying groundwork for quantum opto-mechanics.

Findings

Thermally driven vibrations modulate optical signals in the PCW.

Models accurately predict phase and amplitude modulation near the dielectric band edge.

Provides a basis for sensing mechanical motion at the Standard Quantum Limit.

Abstract

Observations of thermally driven transverse vibration of a photonic crystal waveguide (PCW) are reported. The PCW consists of two parallel nanobeams with a 240 nm vacuum gap between the beams. Models are developed and validated for the transduction of beam motion to phase and amplitude modulation of a weak optical probe propagating in a guided mode (GM) of the PCW for probe frequencies far from and near to the dielectric band edge. Since our PCW has been designed for near-field atom trapping, this research provides a foundation for evaluating possible deleterious effects of thermal motion on optical atomic traps near the surfaces of PCWs. Longer term goals are to achieve strong atom-mediated links between individual phonons of vibration and single photons propagating in the GMs of the PCW, thereby enabling opto-mechanics at the quantum level with atoms, photons, and phonons. The experiments and models reported here provide a basis for assessing such goals, including sensing mechanical motion at the Standard Quantum Limit (SQL).