Investigation of gain and optically pumped lasing in GaInNAs/GaAs multi‐quantum well structures

We present experimental investigation of the optical gain in GaInNAs/GaAs multi-quantum well structures using the variable stripe length method. The amplified spontaneous edge emission was measured at different excitation intensities and stripe lengths. The obtained optical gain values at a temperature of 5 K are typically in the order of 100–150 cm−1, while at room temperature a maximum of 50 cm−1 could be observed. Optically pumped lasing has been detected from cleaved samples at room temperature for excitation densities above 300 kW/cm2.