High speed characterization of 1D-addressable multi-channel VCSELs with SPAD arrays for automotive LIDAR

LUMENTUM's multi-channel VCSELs in combination with SPAD (Single photon avalanche photodiode) receivers can perform "true" solid-state scanning in a single direction. The multi-channel VCSEL along with collimating lens and a horizontal diffuser can be matched with SPAD arrays of different sizes and aspect ratios. In this paper, we show the characterization results of the multi-channel VCSEL with 57 channels and 7J epi architecture, at 5ns pulse width, 0.1% duty cycle from temperature range of -40°C to 125°C. The L-I tests at 25°C yield a threshold current of 0.57A, optical power of 140W, and slope efficiency of 7.21W/A at 20A. The optical power, slope efficiency decreased by only 20% from -40°C to 125°C. The FF divergence at 25°C is about 25° and varies by 1.9° from -40°C to 125°C. The leakage current between different anodes/channels at 85ºC is only 0.27μA for a voltage difference of 50V between the channels. We continue to develop higher current drivers to characterize the VCSELs at higher currents. The next generation VCSELs will have higher junction-count epi, allowing for even higher power and slope efficiency. This scheme of addressable high speed and high power VCSELs tailored for operation with SPAD arrays is a very crucial step towards building allelectronic scanning automotive grade LIDARs.