Fabrication methodology for GaN-based twisted bilayer photonic crystal lasers

Moiré photonics has become a burgeoning research field with many potential applications, one being a new kind of nanoscale, actively tunable semiconductor laser. Stacked bilayer photonic crystal lasers provide possibilities in active tuning using multiple degrees of freedom, including the twist angle and coupling distance between the two layers. Initial demonstrations of moiré photonic crystal lasers with embedded gain material have been shown in devices where the two layers are “merged” into a single layer; however, to fully realize the promise of moiré lasers’ tunability, true bilayer systems must be explored. We demonstrate a fabrication protocol to realize this kind of laser in gallium nitride with embedded indium gallium nitride emitters. We discuss fabrication challenges, including rotational precision, membrane adhesion, and material strain, as well as initial photoluminescent characterization. This research elucidates design questions and limitations that are critical for moving towards novel, tunable, low-threshold lasers in the visible regime.