Transient thermal response of quasi-continuous-wave laser diodes and its impact on saturation power

• Establishing a self-consistent electro-optical-thermal model to investigate transient temperature dynamics of laser bars. • Quantitatively analyzing the transient thermal response variations in laser diodes under varying injection currents. • Establishing the physical connection between transient thermal response and power saturation phenomenon. Quasi-continuous-wave (QCW) high-power laser diodes are critical components in energy-sensitive applications that demand high pulse energies with minimal thermal load, such as laser-driven inertial confinement fusion, precision laser shock peening, and long-range lidar systems. However, thermal constraints fundamentally limit their ability to scale output power. In this study, we develop a self-consistent electro-optical-thermal quasi-3D model to investigate the transient thermal response and the resulting intra-pulse power degradation in QCW laser diodes. By combining numerical simulations and experimental measurements, we show that significant temperature rises during pulse operation (ΔT > 58 °C) are the primary cause of power saturation. Experimental validation was conducted on 808 nm laser bars under aggressive QCW conditions (900 A injection current, 200 μs pulse width, 400 Hz repetition rate, and a heatsink temperature of − 50 °C), achieving a saturation power of 1065 W. Simulation results indicate that the active region temperature increases from − 35.3°C to 22.9 °C within a single 200 μs pulse, leading to a 16.9 % power reduction (from 1147 W to 953 W) due to thermal detuning effects. These findings suggest a critical power enhancement strategy for kilowatt-class laser diodes: implementing dynamic thermal compensation during pulse emission to suppress nonlinear power roll-off in the latter part of the pulse, thereby delaying the onset of power saturation.