2B.3 Final.2025

Abstract
This report investigates 940 nm vertical-cavity surface-emitting lasers (VCSELs) with three junctions (3J). The study focuses on the impact of oxide layers on the electrical and optical performance of these devices under various pulse conditions. Heat accumulation is a significant challenge in VCSELs, and shorter pulse durations reduce heat generation, improving thermal performance and minimizing lateral carrier diffusion in multi-junction structures. The results indicate that incorporating multiple oxide layers enhances carrier confinement, enabling output power exceeding 120 watts with 1.6-nanosecond pulses. However, using a single oxide layer decreases resistance and improves thermal dissipation, while maintaining output power above 100 watts. Spectral measurements revealed a red shift of less than 0.8 nm, corresponding to temperature variations of less than 12°C at 40A current injection. These findings provide valuable insights into the benefits and limitations of multi-junction VCSELs for next-generation sensing applications.