Nanosecond high-pulse energy 1.57 μm KTA optical parametric amplifier with time delay

An efficient two-stage KTi OAO4 optical parametric amplifier(OPA) system with walk-off-compensating alignment is designed. By introducing an extra time delay between the pump pulse and the signal pulse, this OPA architecture is capable of obtaining high optical conversion efficiency and high signal gain simultaneously.Finally, a maximum gain of 98 at the 1.57 μm wavelength is obtained with the signal beam quality of M2 around5.6. The efficiency of the optical conversion from 1.064 to 1.57 μm is around 26%.