New theory of internal Q switching in semiconductor lasers

Single heterostructure lasers: a UK perspective

“…Unsurprisingly, it was found that the odd effects were all connected with what happened to the waveguide when injected carriers caused the refractive index step δμ to be reduced, or even disappear. By 1974 enough had been done to be certain that the critical temperature was that temperature at which the injected carriers cancel any built-in δμ, so the waveguide is too lossy to support lasing [13] and [14]. The 'quenching' region is caused because, contrary to simple theory, the carrier density continues to increase slowly even above threshold, so even below T c a current can be reached where δμ eventually reaches such a small value that lasing cannot take place.…”