Advanced dispersion engineering of a III-Nitride micro-resonator for a blue/UV frequency comb

TL;DR

This paper presents a systematic dispersion engineering method for III-Nitride micro-resonators, enabling broadband blue/UV Kerr frequency combs suitable for quantum and sensing applications.

Contribution

It introduces a novel approach using avoided-crossing in coupled waveguides to achieve strong anomalous dispersion in AlGaN micro-resonators.

Findings

Achieves strong anomalous dispersion in the blue/UV range.

Designs are compatible with current fabrication methods.

Simulations show potential for broadband Kerr frequency combs.

Abstract

A systematic dispersion engineering approach is presented toward designing a III-Nitride micro-resonator for a blue/UV frequency comb. The motivation for this endeavor is to fill the need for compact, coherent, multi-wavelength photon sources that can be paired with, e.g., the $^{171}{\textrm{Yb}}^{+}$ ion in a photonic integrated chip for optical sensing, time-keeping, and quantum computing applications. The challenge is to overcome the normal material dispersion exhibited by the otherwise ideal i.e., low-loss and large-Kerr-coefficient) AlGaN family of materials, as this is a prerequisite for bright-soliton Kerr comb generation. The proposed approach exploits the avoided-crossing phenomenon in coupled waveguides to achieve strong anomalous dispersion in a desired wavelength range. The resulting designs reveal a wide range of dispersion response tunability, and are realizable with the current state-of-the-art growth and fabrication methods for AlGaN semiconductors. Numerical simulations of the spatio-temporal evolution of the intra-cavity field under continuous-wave laser pumping indicate that such a structure is capable of generating a broadband blue/UV bright-soliton Kerr frequency comb.