Spontaneous-emission coupling from multiemitters to the quasimode of a Fabry-Perot microcavity

Using a continuous basis set of optical modes, the spontaneous emission into the lowest-order resonant quasimode of a planar cavity is analyzed for the case of a laterally distributed multiemitter system. We show that for a spatially distributed, randomly phased multiemitter system, the spontaneous rate into the lowest-order cavity quasimode contains a Purcell effect, increases with increasing mode quality factor Q, and saturates when the mode loss becomes less than the dipole dephasing rate. Cooperative effects leading to superradiance for a properly phased multiemitter system are also considered, for which the change in the cavity-confined total spontaneous emission rate can be sizable.