Investigation of photonic crystal surface-emitting laser in blue band based on porous-GaN cladding

Investigated theoretically is a photonic-crystal surface-emitting GaN laser based on surface-etched holes with a porous-GaN cladding layer. The porous GaN has a low refractive index, supporting effective confinement to the resonant mode, and the porous GaN is derived from as-grown GaN, eliminating the lattice mismatch issues typically associated with GaN platforms. Studied systematically is how the photonic-crystal lattice constant, air hole radius, etching depth, and porous-GaN refractive index affect the performance of the laser. The results show that the laser exhibits optimal overall performance when the lattice constant is 216 nm and the hole radius is 60 nm. The etching depth can be chosen between 30 and 100 nm, and the porous-GaN refractive index is preferably in the range of 1.7–1.9. The research achieves a quality factor as high as 1.9 × 10⁴, with a photonic-crystal-layer confinement factor of 4.24% and an active-layer confinement factor of 21.8%, along with a low threshold gain of 77 cm⁻¹.