Gain saturation in (In,Ga)N/GaN/(Al,Ga)N laser structures

We performed systematic studies of the optical gain and its saturation in (In,Ga)N/GaN/(Al,Ga)N laser structures in dependence on photon energy, excitation density and number of quantum wells. The optical gain and its saturation were obtained by means of the variable stripe-length method under quasi-stationary conditions. The unsaturated gain factor increases with increasing excitation power. i.e increasing modal gain, and reaches its maximum at energies slightly below the spectral position of the gain maximum. High unsaturated gain factors of up to 40 dB at 300 K have been measured.