Systematic dispersion engineering of crystalline microresonators for broadband and coherent frequency comb generation

TL;DR

This paper demonstrates how ultraprecision machining of crystalline microresonators enables precise dispersion engineering, leading to the generation of broadband, coherent frequency combs with suppressed mode interactions.

Contribution

It introduces a fabrication approach that allows for precise dispersion control in crystalline microresonators, enabling broadband and coherent frequency comb generation.

Findings

High-precision resonators suppress spatial mode interactions.

Generation of smooth dissipative Kerr soliton combs.

Broadband frequency combs beyond the telecommunication C-band.

Abstract

Ultraprecision machining offers a powerful route to dispersion control in crystalline microresonators, allowing the design of waveguide geometries for tailoring the spectrum of microresonator frequency combs. By precisely designing the geometry, both group-velocity and higher-order dispersions can be engineered across a broad wavelength range. However, despite their promising features, such advantages have remained largely unexplored due to fabrication challenges. Here, we demonstrate that resonators shaped by ultrapecision machining exhibit high precision and strongly suppressed spatial mode interactions, facilitating the generation of smooth dissipative Kerr soliton combs and broadband frequency combs beyond the telecommunication C-band. These results underscore the effectiveness of precision geometry control for realizing coherent and broadband microcombs on crystalline photonic platforms.