A model of microcavity semiconductor lasers in which both the cavity field and the gain medium are quantized is presented. The equation of motion for the elements of the reduced density matrix for the field in the photon number representation is developed and numerically solved to find the steady-state photon number distribution and the laser linewidth for a variety of operating conditions. For typical semiconductor microcavity operating conditions, the intensity noise is smaller and the laser linewidth is larger for lasers with a larger fraction of spontaneous emission into the cavity mode. However, for very-low-loss microcavity lasers, if the rate of spontaneous emission into the cavity mode exceeds the loss rate, the laser can appear to turn on at pump rates for which the gain medium is not inverted. In this anamolous regime, the laser intensity noise increases with an increased fraction of spontaneous emission into the cavity mode.
© 2007 Optical Society of America
Original Manuscript: August 22, 2006
Revised Manuscript: March 12, 2007
Manuscript Accepted: April 12, 2007
Published: July 19, 2007
Hassan S. Ashour, Michael Sokol, Leno M. Pedrotti, and Perry R. Rice, "Quantum theory of semiconductor lasers in the photon number representation," J. Opt. Soc. Am. B 24, 1995-2005 (2007)