Measurement of optical gain and optical internal loss in GaN-based laser

To assess the performance of a semiconductor laser,knowledge of gain and loss at a known pumping level is essential.Both the gain and the loss coefficients were obtained through analyzing amplified spontaneous emission (ASE) measured with variable stripe length (VSL) method,and serious gain saturation phenomenon was observed in the process.The results confirm the feasibility of the VSL method in studying the performance of GaNLD samples.Performance of LDs with two different structures in gain and gain saturation were compared through VSL method,and the reason that leads to the differen ce was discussed.