Mode locking of a homogeneous gain laser through temporally modulated phase-conjugate reflectivity

Mode locking of a homogeneous gain laser by a temporally modulated phase-conjugate mirror is investigated through a dispersive model. Phase conjugation is assumed to be due to degenerate four-wave mixing with external pumps consisting of two trains of temporally Gaussian pulses. Approximate solutions are found in terms of Gaussian pulses whose width depends on the duration of the pump pulses, the coherence time of the homogeneous gain medium, and the relaxation time of the nonlinear medium. Numerical solutions are in excellent agreement with the Gaussian-pulse solutions.