Frequency control of photonic crystal membrane resonators by mono-layer deposition

TL;DR

This paper investigates how thin film deposition and monolayer attachment affect the resonance frequency of GaAs photonic crystal membrane resonators, revealing potential for controlled tuning and surface passivation.

Contribution

It demonstrates the use of self-assembled monolayers to precisely shift and passivate the surface of photonic crystal resonators, introducing a novel method for frequency control.

Findings

Spectral shifts of several nanometers caused by cryo-gettering.

Heating resets the resonance drift.

Monolayers induce discrete resonance frequency steps.

Abstract

We study the response of GaAs photonic crystal membrane resonators to thin film deposition. Slow spectral shifts of the cavity mode of several nanometers are observed at low temperatures, caused by cryo-gettering of background molecules. Heating the membrane resets the drift and shielding will prevent drift altogether. In order to explore the drift as a tool to detect surface layers, or to intentionally shift the cavity resonance frequency, we studied the effect of self-assembled monolayers of polypeptide molecules attached to the membranes. The 2 nm thick monolayers lead to a discrete step in the resonance frequency and partially passivate the surface.