Study on the saturation phenomenon of optical gain in green laser structures under varying excitation conditions

This study investigates the saturation phenomenon of optical gain in green laser diode structures, which are crucial for III-Nitrides based optical devices. Using the Variable Stripe Length Method (VSLM), we examine how optical gain is influenced by excitation density and optical cavity length. The research highlights two major challenges: in-plane compositional inhomogeneity in the InGaN layer as the In composition increases, and the internal electric fields arising from piezoelectric and spontaneous polarization effects, which reduce the overlap integral between electron-hole pairs and hinder luminescent recombination. Understanding these factors is key to improving optical gain and achieving high-performance green laser diodes with linear gain characteristics.