Design of GaN-based photonic crystal surface emitting lasers with top TiO2 photonic crystals

Abstract

We designed GaN-based blue photonic crystal surface emitting lasers (PCSELs) by incorporating a TiO2 photonic crystal (PhC) layer on top of the GaN surface. An AlGaN cladding layer was designed under the active region to form a waveguide-like cap layer. The dimension of the cap layer, the lattice constant of PhC, the hole radius, and the layer thickness were investigated to optimize the structure design in view of the PhC confinement factor and gain threshold. With a depth of 100 nm of the PhC layers, a hole radius of 40 nm, and a thickness of 100 nm of GaN layers above and below multiple quantum wells (MQWs), the PhC confinement factor of greater than 10% and the gain threshold below 400 cm−1 can be realized. Furthermore, the photonic band diagram is calculated, which shows that the designed PCSELs are operated at the Γ1 band edge with the lowest pump energy. This work demonstrates the potential of excellent properties in the future surface emitting blue laser sources.