Khashayar Ghaffari
Ansys Employee

Hi,

Thank you for your question. Can you tell me what are some of the changes you made to the original example? As you suggested it is expected for the lasing to occur once the gain surpasses the threshold (the loss due to different mechanisms such as non-radiative recombination, mirror loss, and free carrier absorption i.e. waveguide loss). There is likely one or few adjustments needed to the updated model you are using. We are not allowed to download or upload files on the forum, but if you could share some information about the differences in your file compared to the original example we can try to comment more specifically.

Best regards