  We propose cooperative two-photon lasing in two quantum dots coupled to a
single mode photonic crystal cavity. We consider both quantum dots are driven
either incoherently or coherently using external pump. We incorporate
exciton-phonon coupling using polaron transformed master equation. Using
quantum laser theory, single and multi-photon excess emission (difference
between emission and absorption) into cavity mode are investigated. The single
and two-photon excess emission contribute to cavity photons, predominantly.
Varying the pump strength can lead to single-photon excess emission change from
negative to positive and thus by appropriately selecting pump strength
single-photon excess emission can be made negligible.
