Numerical solutions of the rate equations for pulsed reflected mode (PRM), pulsed transmission mode (PTM) and normal operation have been performed by computer in terms of FLPL operating parameters. The results are analyzed and compared. Some primary factors effecting on photon density in the cavity for PTM operation are investigated. The principle results of theoretical investigation have been confirmed by experiments. The pulse duration compression from μs to 3ns has been obtained. The peak power was raised from decades kW to MW by PTM operation.