One Million Quality Factor Integrated Ring Resonators in the Mid-Infrared

TL;DR

This paper demonstrates high-quality silicon germanium ring resonators operating in the mid-infrared with quality factors up to one million, enabled by advanced fabrication techniques, advancing integrated photonics in this spectral range.

Contribution

It reports the first realization of ultra-high Q-factor ring resonators in silicon germanium for mid-infrared applications, showcasing fabrication advancements and optical phenomena.

Findings

Q-factors up to one million achieved

Observation of degeneracy lifting between CW and CCW modes

Demonstration of optical bistability in the resonators

Abstract

We report ring resonators on a silicon germanium on silicon platform operating in the mid-infrared wavelength range around 3.5 - 4.6 {\mu}m with quality factors reaching up to one million. Advances in fabrication technology enable us to demonstrate such high Q-factors, which put silicon germanium at the forefront of mid-infrared integrated photonic platforms. The achievement of high Q is attested by the observation of degeneracy lifting between clockwise (CW) and counter-clockwise (CCW) resonances, as well as optical bistability due to an efficient power buildup in the rings.