Laser rate equation
= Laser rate equation
A <laser rate equation> approximates coupled evolution of <population inversion> and intracavity <photon number>, including pumping, <spontaneous emission>, <stimulated emission> and <optical cavity> losses. A simple model is $\dot S=[g(N)-1/\tau_c]S$, $\dot N=R_p-N/\tau_u-g(N)S$, where compatible normalizations absorb mode-volume factors. Large excess <optical gain> drives rapid field growth until inversion depletion reduces it below threshold.