  Optical pump-probe signals can be viewed as work done by the matter while
transferring the energy between two coherent baths (from pump to probe). In
thermodynamics a heat engine, such as laser, is a device which performs similar
work but operating between two thermal baths. We propose an "incoherent"
control procedure for the optical signals using the physics of quantum heat
engine. By combining a coherent laser excitation of electronic excited state of
molecule with thermal relaxation we introduce an effective thermal bath
treating stimulated emission of probe photons as work performed by the heat
engine. We optimize power and efficiency for the pump-probe signal using
control parameters of the pump laser utilizing four level molecular model in
strong and weak coupling regime illustrating its equivalence with the
thermodynamic cycle of the heat engine.
