# Blue Microlasers Integrated on a Photonic Platform on Silicon

## TL;DR

This paper demonstrates the integration of blue microdisk lasers on a silicon photonic platform, showcasing lasing in a nanophotonic circuit with high quality factors and evanescent coupling.

## Contribution

It presents the first integration of III-nitride microdisk lasers with silicon photonics, including design, fabrication, and lasing demonstration in a nanophotonic circuit.

## Key findings

- Loaded quality factors >2000 for whispering gallery modes
- Lasing observed in 3 μm diameter microdisks under pulsed excitation
- Efficient evanescent coupling achieved with sub-100 nm gaps

## Abstract

The main interest of group-III-nitride nanophotonic circuits is the integration of active structures and laser sources. A photonic platform of group-III-nitride microdisk lasers integrated on silicon and emitting in the blue spectral range is demonstrated. The active microdisks are side-coupled to suspended bus waveguides, and the coupled emission is guided and outcoupled to free space using grating couplers. A small gap size of less than 100 nm between the disk and the waveguide is required in the blue spectral range for optimal evanescent coupling. To avoid reabsorption of the microdisk emission in the waveguide, the quantum wells are etched away from the waveguide. Under continuous-wave excitation, loaded quality factors greater than 2000 are observed for the whispering gallery modes for devices with small gaps and large waveguide bending angles. Under pulsed excitation conditions, lasing is evidenced for 3 $\mu$m diameter microdisks integrated in a full photonic circuit. We thus present a first demonstration of a III-nitride microlaser coupled to a nanophotonic circuit.