Control of Second Harmonic Generation in Doubly Resonant Aluminum Nitride Microrings to Address Rubidium Two-Photon Clock Transition

TL;DR

This paper demonstrates precise control of second harmonic generation in aluminum nitride microrings by analyzing phase-matching conditions, enabling targeted wavelength generation for rubidium atomic transitions on-chip.

Contribution

It introduces a method to precisely tune microring resonators for specific nonlinear optical processes, particularly for rubidium two-photon transitions.

Findings

Achieved phase-matching at the rubidium two-photon transition wavelength

Demonstrated control over resonance wavelength via microring design parameters

Validated the approach for targeting specific wavelengths with picometer precision

Abstract

Nonlinear optical effects have been studied extensively in microresonators as more photonics applications transition to integrated on-chip platforms. Due to low optical losses and small mode volumes, microresonators are demonstrably the state-of-the-art platform for second harmonic generation (SHG). However, the working bandwidth of such microresonator-based devices are relatively small, presenting a challenge for applications where a specifically targeted wavelength needs to be addressed. In this work, we analyzed the phase-matching window and resonance wavelength with respect to varying microring width, radius and temperature. A chip with precise design parameters was fabricated with phase-matching realized at the exact wavelength of two-photon transition of 85-Rubidium. This procedure can be generalized to any target pump wavelength in the telecom-band with picometer precision.