Continuous-wave Raman Lasing in Aluminum Nitride Microresonators

TL;DR

This paper demonstrates continuous-wave Raman lasing in high-quality aluminum nitride microresonators, achieving low thresholds, high efficiency, and second-order lasing with high output power, advancing integrated photonics for mid-infrared applications.

Contribution

First demonstration of continuous-wave Raman lasing in AlN microresonators with selective phonon excitation and high power output, supported by theoretical analysis.

Findings

Single-mode Raman lasing with low threshold achieved.

Selective excitation of specific phonons observed.

Second-order Raman lasing with 11.3 mW output power demonstrated.

Abstract

We report the first investigation on continuous-wave Raman lasing in high-quality-factor aluminum nitride (AlN) microring resonators. Although wurtzite AlN is known to exhibit six Raman-active phonons, single-mode Raman lasing with low threshold and high slope efficiency is demonstrated. Selective excitation of A$_1^\mathrm{TO}$ and E$_2^\mathrm{high}$ phonons with Raman shifts of $\sim$612 and 660 cm$^{-1}$ is observed by adjusting the polarization of the pump light. A theoretical analysis of Raman scattering efficiency within ${c}$-plane (0001) of AlN is carried out to help account for the observed lasing behavior. Bidirectional lasing is experimentally confirmed as a result of symmetric Raman gain in micro-scale waveguides. Furthermore, second-order Raman lasing with unparalleled output power of $\sim$11.3 mW is obtained, which offers the capability to yield higher order Raman lasers for mid-infrared applications.