High performance multi-junction VCSELs for LiDAR applications
Heng Liu, Pei Miao, Yao Xiao, Chang Liu, Zhicheng Zhang, Jun Wang
Abstract
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<sup>2</sup> exhibit power density higher than 1800 W/mm<sup>2</sup> and divergence angle lower than 21 degree (1/e<sup>2</sup>) with 15A peak current, 10kHz 10 nano-second pulsed (FWHM) driver.