Date: 2023/06/28, 08:40 AM (GMT+2)
Dr. Amir Sharghi
Location: SPIE Digital Optical Technologies, Munich/ Germany
LIV curves are fundamental measurement of laser diodes to determine electrical and optical operating characteristics. LIV curves consist of L-I curves (optical intensity against current) and V-I curves (voltage against current). LIV curves determine power conversion efficiency, threshold current, slope efficiency, kinks, rollover point and more. LIV curves are widely used at various stages since it is critical to identify failed DUTs early in the manufacturing process.
LIV curves are always measured for the DUTs with single emitter or for DUT as a whole when consist of many emitters. Detailed and comprehensive LIV test and beam analysis of each single emitters of an array is the focus of this study. We extended existing one-dimensional LIV test and beam analysis including beam numerical aperture, M2 and beam waist to each single emitters of the laser diode array at well-controlled conditions. Our experimental design consist of camera based radiant power measurement. This approach allows parallelization of the measurements, which reduces overall measurements time, and investigation on the cross-talk between individual emitters. We analyzed electrical and optical differences within emitters of a VCSEL array and as well with the array as a whole. The accepted range of variation can be set in order to identify underperforming or out-of-specification single emitters. Therefor defect or deficient laser diodes are detected at early stages of the manufacturing process, saving time and money. Such comprehensive characterization of arrays individual emitters is crucial for demanding applications such as facial recognition, 3D sensing, in cabin sensing, LiDAR and ranging.