Overcoming LIV Test Challenges Using a High Channel Density SMU Solution
Application Notes
A critical component for imaging, sensing technology, and data communication is the vertical-cavity surface-emitting laser (VCSEL). One of the advantages of VCSELs is the ability to conduct testing at the wafer level during the early stages of the manufacturing process. In contrast, testing for other edge-emitting semiconductor lasers is typically performed at the end of the manufacturing cycle, when the products have reached their final stage of production. This testing approach allows for early detection of component failures, resulting in significant time and cost savings by identifying defective devices prior to packaging. The light-current-voltage (LIV) sweep test is a fundamental measurement to determine the operating characteristics of optical sources such as laser diodes (LDs) and VCSELs. Usually, the LD module combines a laser diode and a photodetector (PD) for monitoring the output and providing feedback for controlling the laser power. Figure 1 shows how LIV tests aim to evaluate light-current characteristics, threshold current, slope efficiency, kink, and forward voltage.