Monolithic integration of ultraviolet microdisk lasers into photonic circuits in a III-nitride-on-silicon platform

TL;DR

This paper demonstrates the monolithic integration of ultraviolet microdisk lasers into photonic circuits on a III-nitride on silicon platform, achieving lasing at 374-399 nm with low threshold energies and high quality factors.

Contribution

It introduces a novel monolithic integration method for UV microdisk lasers in a III-nitride-on-silicon platform with high quality factors and low lasing thresholds.

Findings

Achieved quality factors up to 3500.

Observed lasing from 374 nm to 399 nm.

Low threshold energies of 0.14 mJ/cm² per pulse.

Abstract

Ultraviolet microdisk lasers are integrated monolithically into photonic circuits using a III-nitride on silicon platform with gallium nitride (GaN) as the main waveguiding layer. The photonic circuits consist of a microdisk and a pulley waveguide terminated by out-coupling gratings. We measure quality factors up to 3500 under continuous-wave excitation. Lasing is observed from 374 nm to 399 nm under pulsed excitation, achieving low threshold energies of $0.14 ~\text{mJ/cm}^2$ per pulse (threshold peak powers of $35 ~\text{kW/cm}^2$). A large peak to background dynamic of around 200 is observed at the out-coupling grating for small gaps of 50 nm between the disk and waveguide. These devices operate at the limit of what can be achieved with GaN in terms of operation wavelength.