New Advances in Generation of High Repetition Rate Burst Mode Laser Output

摘要

It is demonstrated that the incorporation of variable pulse duration flashlamp power supplies into an Nd:YAG burst mode laser system results in very substantial increases in the realizable energy per pulse, the total pulse train length, and uniformity of the intensity envelope. Trains of twenty pulses at burst frequencies of 50 kHz and 20 kHz, respectively, are demonstrated with individual pulse energy, at 1064 nm, of 220 mJ and 400 mJ, respectively. Conversion efficiency to the second (532 nm) and third (355 nm) harmonic wavelengths of –50% and 35-40%, respectively is also achieved. Use of the third harmonic output of the burst mode laser as a pump source for a simple, home built Optical Parametric Oscillator produces pulse trains of broadly wavelength tunable output. Sum-Frequency mixing of OPO signal output at 622 nm with residual output from the 355 nm pump beam is shown to produce uniform bursts tunable output at –226 nm, with individual pulse energy of –0.5 mJ. Time correlated NO Planar Laser Induced Fluorescence (PLIF) image sequences are obtained in a Mach 3 wind tunnel at 500 kHz representing, to our knowledge, the first demonstration of NO PLIF imaging at repetition rates exceeding 10's of Hz.