CW-Pumped Amplified Spontaneous Emission From Thermally Evaporated CsPbBr₃ Films

Lead halide perovskites are widely reported as promising optical gain media for optoelectronic applications in the short-pulse regime. However, their operation under continuous-wave excitation remains severely limited by thermal accumulation and gain instability. Here, we present a systematic study of amplified spontaneous emission under long-pulse and continuous-wave excitation in thermally evaporated CsPbBr₃ thin films, providing direct insight into the limits of sustained optical gain in perovskite materials. By correlating excitation pulse duration, substrate thermal conductivity, temperature-dependent emission properties, and time-resolved carrier dynamics, we establish a physical framework linking thermal dissipation to gain stability. We identify excitation-time thresholds and define optimal operating regimes, demonstrating sustained amplified spontaneous emission for pulse widths up to 30 µs in films without encapsulation or additional post-processing. Our results reveal that light-induced thermal accumulation is the dominant mechanism limiting amplified spontaneous emission under extended excitation and highlight thermal management as a critical design parameter for steady-state optical gain. These findings provide practical design rules for perovskite gain media and represent a key step toward electrically pumped, continuous-wave-performing perovskite superluminescent and laser diodes.