The light-current-voltage (LIV) sweep test is a fundamental measurement to determine the operating characteristics of a laser diode (LD). In the LIV test, current applied to the laser diode is swept and the intensity of the resulting emitted light is measured using a photo detector. This article provides a comprehensive overview of laser diode testing, a critical process for ensuring high performance, reliability, and long lifetimes. It explains why testing is essential at various stages, from development and manufacturing quality control to the burn-in process for eliminating. In this white paper, we discussed what an LIV Test for laser diodes is and the significance of L-I-V test in detecting defects in early production stages. We also discuss the measurement challenges of this test. Munich, March 2022 – At LASER WoP 2022 Instrument Systems will be showcasing its extensive test portfolio of IR emitters and VCSELs.