Performance of a CW pumped Nd:YVO4 amplifier with kHz pulses

Until recently, simple and reliable high repetition-rate laser sources with nanosecond pulses much shorter than from conventional A-O Q-switch lasers were not available. However over the past 2 years we have developed such lasers based on proprietary fast E-O switching technology, which allows designs delivering pulses and subnanosecond jitter for good synchronisation. The technology provides pulses with multi-kW peak power and repetition-rates to .Most recently, the performance of these short pulse lasers has been developed further by implementing oscillator/amplifier (master oscillator and power amplifier, MOPA) technology which increases the output to average power. Here we report on a simple model that has been used to predict the performance of the CW pumped Nd:YVO4 amplifier used in the MOPA laser. The model is based on the well-known expressions for the saturated gain applying to laser pulses, but more usually applied to pulse-excited amplifiers. The model is shown to allow a good interpretation of the amplifier behaviour for kHz pulses and to be a useful tool for predicting the performance of the MOPA laser

Simplified analysis of double pass amplification with pulse overlap and application to Nd:YVO₄ laser

We derive simple and convenient expressions for two-pass saturated amplification with pulse overlap. These have the same form as the single-pass Franz–Nodvik equations but with a factor of two in front of the cross-section for stimulated emission. The predicted decrease in energy extraction efficiency when there is pulse overlap compared with sequential passes agrees well with earlier numerical modelling. This approach has been extended to analyse a two-pass Nd:YVO4 amplifier (diode pumped 2 mm long 1% doped crystal) operated with nanosecond pulses delivered at rates up to 20 kHz and taking account of the Gaussian beam profile. An estimate of γ = 1 × 10-15 cm3 s-1 for the up-conversion macro-parameter was found to provide a consistent value for the length-averaged gain coefficient and the effective gain lifetime of the amplifier for the pump conditions used

Solid-state Raman laser generating

A new Raman oscillator is described based on a diode end-pumped Nd:YAG laser and an intra-cavity rubidium titanyl phosphate (RTP) crystal that serves as the active Q-switch. This compact and robust laser generates <1 ns, kilohertz pulses at 1096 nm with a 1064 nm pump and has potential for ?1480 nm eye-safe operation using a 1340 nm pump. Based on rate equation modelling a Raman gain of ?1.7–2.2 cm/GW at 1064 nm is estimated for RTP