Realization of high-Q/V bichromatic photonic crystal cavities defined by an effective Aubry-Andr\'e-Harper potential

TL;DR

This paper demonstrates the design, fabrication, and optical characterization of bichromatic photonic crystal cavities based on an Aubry-André-Harper potential, achieving ultra-high-Q factors in silicon membranes.

Contribution

It introduces a novel photonic crystal cavity design utilizing a bichromatic potential, enabling high-Q/V ratios with straightforward implementation and scalability.

Findings

Achieved Q-factors in the 1 million range.

Demonstrated the design's generality and scalability.

Validated the confinement mechanism through resonant scattering.

Abstract

We report on the design, fabrication and optical characterization of bichromatic photonic crystal cavities in thin silicon membranes, with resonances around 1550 nm wavelength. The cavity designs are based on a recently proposed photonic crystal implementation of the Aubry-Andr\'e-Harper bichromatic potential, which relies on the superposition of two one-dimensional lattices with non-integer ratio between the periodicity constants. In photonic crystal nanocavities, this confinement mechanism is such that optimized figures of merit can be straightforwardly achieved, in particular an ultra-high-Q factor and diffraction-limited mode volume. Several silicon membrane photonic crystal nanocavities with Q-factors in the 1 million range have been realized, as evidenced by resonant scattering. The generality of these designs and their easy implementation and scalability make these results particularly interesting for realizing highly performing photonic nanocavities on different materials platforms and operational wavelengths.