Is There a Linewidth Theory for Semiconductor Lasers?

Semiconductor laser generation begins at a critical injection when the gainand loss spectra touch each other at a singular frequency. In the framework ofthe standard (Schawlow-Townes-Lax-Henry) theory, the finite linewidth resultsfrom the account of fluctuations associated with the random spontaneousemission processes. This approach is based on the assumption that in themean-field approximation the singular frequency generation persists forinjection levels higher than critical. We show that this assumption in theframework of the Boltzmann kinetic equation for electrons and photons isinvalid and therefore the standard description of semiconductor laser linewidthlacks theoretical foundation. Experimental support of the standard theory isalso questionable.