Fabrication of Ultra-High Q Silica Microdisk Using Chemo-Mechanical Polishing

TL;DR

This paper presents a method to fabricate silica microdisks with ultra-high optical quality factors exceeding 10^8 by incorporating chemo-mechanical polishing into the manufacturing process, reducing surface roughness and improving performance.

Contribution

Introducing chemo-mechanical polishing into microdisk fabrication to significantly enhance surface quality and optical Q factors beyond previous limits.

Findings

Achieved Q factors over 10^8 at 1550 nm.

Surface roughness reduction is key to high Q performance.

Water molecule absorption dominates Q degradation at 1550 nm.

Abstract

Here we demonstrate that adding a chemo-mechanical polishing (CMP) procedure to conventional photolithography, a silica microdisk with ultra-high quality factors ($>10^8$) can be fabricated. By comparing with the intrinsic optical quality factor (Q) measured at 970~nm, we observe that due to the significantly reduced surface roughness, at 1550~nm wavelength the water molecule absorption at the cavity surface supersedes Rayleigh scattering as the dominant factor for Q degradation.