Highly efficient, widely tunable, 10-Hz parametric amplifier pumped by frequency-doubled femtosecond Ti:sapphire laser pulses

We report a 10-Hz, highly efficient, widely tunable (from the visible to the IR), broadband femtosecond optical parametric generator and optical parametric amplifier (OPA) in BBO, LBO, and CBO crystals pumped by the frequency-doubled output of a regeneratively amplified Ti:sapphire laser at 400 nm. The output of the system is continuously tunable from 440 nm to 2.5 mu m with a maximum overall efficiency of similar to 25% at 670 nm and an optical conversion efficiency of more than 36% in the OPA stage. The effects of the seed beam energy, the type of the crystal and the crystal length, and the pumping energy of the output of the OPA, such as the optical efficiency, the bandwidth, the pulse duration, and the group velocity mismatch between the signal and the idler and between the seeder and the pump, are investigated. The results provide useful information for optimization of the design of the system. (C) 1998 Optical Society of America.