High performance multi-junction VCSELs for LiDAR applications

High power density VCSELs are attracting attentions in the field of LiDAR applications. Multi-junction VCSEL is the key technology to obtain high power density. High slope efficiency, high filling factor and small divergence angle are the straight-forward research directions to realize this high performance multi-junction VCSEL array. We optimize the epitaxial design and fabrication process, such as tunnel junction, oxidation layer and array layout. The progress on high performance multi-junction VCSEL array emitting around 940 nm is reported. Selectively oxidized, top-emitting VCSEL emitter array with 59.7% power conversion efficiency and slope efficiency of 8.3 W/A are developed as the basic laser source targeting at the LiDAR applications. The fabricated VCSEL array devices with emitting area of 234*250 um(2) exhibit power density higher than 1800 W/mm(2) and divergence angle lower than 21 degree (1/e(2)) with 15A peak current, 10kHz 10 nano-second pulsed (FWHM) driver.