Operation conditions for a picosecond laser with an aberration thermal lens under longitudinal pulsed diode pumping

The dependence of the repetition frequency range that provides stable operation of a picosecond laser with longitudinal pulsed diode pumping on the parameters of the laser cavity and the thermal lens induced in the active element is analysed. The results of calculating the radius of the lower cavity mode as a function of pump beam average power and diameter are reported. Based on the measurements by the probe-beam method, the adequacy of the presented model of aberration thermal lens is demonstrated for the cases of uniformly doped Nd:YAG and composite YAG/Nd:YAG active elements upon tuning the pump pulse repetition frequency within the range of 0 — 1 kHz. The ways for implementing stable generation of millijoule pulses in a specified repetition frequency range are discussed.