Characterization of long-cavity GaN vertical-cavity surface-emitting lasers with a topside dielectric lens

Abstract We present a high-performance GaN-based vertical-cavity surface-emitting laser with a long cavity (70 λ ), nanoporous GaN distributed Bragg reflector (DBR), and topside dielectric lens, achieving room-temperature continuous-wave operation up to thermal rollover at 34 kA cm −2 and a peak output power of 2.7 mW. Process optimizations significantly improved the lens surface quality, reducing optical losses. The long cavity improved thermal management, leading to a measured thermal impedance of 607 K W −1 , the lowest reported for GaN vertical-cavity surface-emitting lasers (VCSELs) with a nanoporous DBR. Spatial mode analysis revealed structured Laguerre–Gaussian-like patterns, with evidence of coherent speckle. These results demonstrate the viability of long-cavity designs for high-power GaN VCSELs.