S.P. Ng

Deterministic chaos in a diode-pumped Nd:YAG laser passively Q switched by a Cr 4+ :YAG crystal

We report the experimental observation and numerical simulation of deterministic chaos in a diode-pumped Nd:YAG solid-state laser that is passively Q switched by a Cr4+:YAG crystal saturable absorber. We show that apart from the stable Q-switched operation the laser can also exhibit complicated nonlinear dynamics, including the period-doubling route to chaos and periodic windows.

Satellite pulse generation in diode-pumped passively Q-switched Nd:GdVO/sub 4/ lasers

We have both experimentally and numerically investigated the satellite pulse generation in diode-pumped passively Q-switched Nd:GdVO 4 lasers with Cr4+:YAG saturable absorber. We show experimentally that satellite pulse generation is a general effect of the lasers under strong pumping, and its formation is always associated with the appearance of strong Q-switched pulses. Satellite pulse generation of the lasers is further numerically simulated based on a coupled rate-equation model. Our numerical simulations show that the phenomenon is caused by the finite lifetime of the lower laser energy level of the lasers

Coherent polarization locking of a diode emitter array

We present our work on the coherent combining of an array of diode emitters in a conventional diode bar configuration using the coherent polarization locking technique. An external laser cavity is designed so that the diode emissions from four diode emitters are spatially overlapped and passively phase locked via a series of birefringent walk-off crystals and a polarizing beam splitter. This concept was experimentally demonstrated up to 1030 mW of coherently combined power and was shown to increase the laser brightness of the diode bar by approximately 50 times.

Polarization-resolved study of diode-pumped passively Q-switched Nd:GdVO4 lasers.

By using the natural birefringence of an a-cut Nd:GdVO(4) crystal, we experimentally investigate laser operation under different light polarizations (pi- and sigma-polarized emissions) and compare their performance. The laser performance is further compared with a diode-pumped c-cut Nd:GdVO(4) laser of the same parameters. We show experimentally that the c-cut Nd:GdVO(4) laser could have good passively Q-switched performance in a low-pump-power region but is influenced by other intrinsic laser effects, such as the thermally induced cavity losses; its performance is severely degraded under high pump power. The best passively Q-switched performance obtained in our experiments is from the a-cut pi-polarized laser, which gives the narrowest pulse of 5.4 ns with the highest peak power of 20 kW. Our experimental results show that, to achieve the best performance of the passively Q-switched laser operation, an overall consideration of laser parameters is important.

High power diode-pumped Nd:GVO/sub 4/ lasers passively Q-switched by Cr/sup 4+/:YAG crystals

We report on high power diode pumped Nd:GdVO/sub 4/ lasers passively Q-switched by Cr/sup 4+/:YAG crystals of different initial transmission. Q-switched pulses of duration of 6 ns and peak power of 26.4 kW have been obtained.