Simplified Aluminum Nitride Processing for Low-Loss Integrated Photonics and Nonlinear Optics

TL;DR

This paper introduces a simplified fabrication method for aluminum nitride microresonators using a single silicon nitride mask and conductive polymer, achieving high quality factors and enabling various nonlinear optical phenomena.

Contribution

A novel, streamlined fabrication process for AlN microresonators that simplifies production and enhances nonlinear optical performance.

Findings

Achieved Q factors up to one million in AlN microresonators.

Demonstrated nonlinear phenomena including frequency combs, Raman lasing, and third harmonic generation.

Simplified fabrication process reduces complexity and improves device performance.

Abstract

Aluminum nitride (AlN) is an extremely promising material for integrated photonics because of the combination of strong \c{hi}2 and \c{hi}3 nonlinearities. However, the intrinsic hardness of the material and charging effects during electron beam lithography make AlN nanofabrication a challenging process. Conventional approaches often require multiple hard masks and a metal mask to fabricate nanostructures. In this letter, we report a novel, simple method to fabricate AlN microresonators by using a single layer of silicon nitride mask combined with a thin conductive polymer layer. The conductive layer can be conveniently removed during developing without requiring an additional etching step. We achieve high intrinsic quality (Q) factors up to one million in AlN microresonators and demonstrate several nonlinear phenomena within our devices, including frequency comb generation, Raman lasing, third harmonic generation and supercontinuum generation.