Lumentum’s short pulse single-junction VCSEL arrays are currently being deployed in Time of Flight (ToF) sensors for short-range Light Detection and Ranging (LIDAR) applications in consumer electronics. However, single-junction VCSEL devices have a slope efficiency (SE) of only around 1.1 W/A making them unsuitable for longer range, higher power applications. With the rise of autonomous vehicle market, there is a need for ultra-short pulse, high peak power VCSELs for medium to long-range LIDAR systems. Multi-junction VCSELs are ideal candidates for this segment. The multi-junction VCSEL consists of stacked gain regions connected by highly doped tunnel junctions. An electron which radiatively recombines with a hole in one gain region, generating a photon, can then tunnel back into the conduction band via the highly doped region and is again available to generate another photon in the subsequent gain region, and so on. The total photons or output power scales with the number of junctions in the device. The optical power density and chip size are critical parameters of a LIDAR module. In this paper, we report the results of compact multi-junction arrays capable of delivering very high peak power.
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