The role of VCSELs in 3D sensing and LiDAR
Matthew Dummer, Klein Johnson, Sara Rothwell, Karim Tatah, Mary K. Hibbs-Brenner
Abstract
3D sensing is being widely adopted in consumer, industrial and automotive markets. As an illumination source, VCSELs provide a combination of high efficiency, miniaturized packaging, fast pulse rise times and minimal spectral shift with temperature. This paper will describe advances in VCSEL technology that address the requirements of 3D sensing and LiDAR applications. 3D Sensing based on structured light requires power efficient VCSELs with a narrow beam divergence, compatible with the optics that produce a spot pattern in the far field. Time of Flight or LiDAR also requires high power efficiency, as well as fast rise times for good resolution in the 3rd dimension. For consumer applications, compactness of the illumination module is important, while all versions of 3D sensing benefit from the VCSEL’s narrow spectrum and low spectral shift with temperature. In this paper we will describe recent advances in VCSEL technology that enable improvements in 3D sensing systems. This includes efficiency improvements (greater than 60% power conversion efficiency), multi-junction VCSEL designs (up to 5 junctions in a device), and flip-chip back-side emitting VCSELs that enable miniaturization of illumination modules and large-scale addressability. In addition, we will describe module level integration of illumination sources, particularly for Time of Flight (TOF) and LiDAR applications, that incorporate VCSEL, driver, monitor diode, eye safety measures and optics.