Frequency-doubled Nd:YAG MOPA laser system with programmable rectangular pulses up to 200 microseconds

TL;DR

This paper presents a compact, programmable Nd:YAG laser system capable of producing high-energy, flat-top pulses up to 200 microseconds, with stable second harmonic generation at 532 nm, suitable for precision applications.

Contribution

The development of a novel, compact, and programmable Nd:YAG MOPA laser system with flat-top pulse shaping and efficient second harmonic generation at 532 nm.

Findings

Generated 520 mJ, 2.6 kW peak power pulses at 1064 nm

Produced 262 mJ, 1.3 kW peak power at 532 nm with high stability

Achieved flat-top temporal and spatial beam profiles

Abstract

A compact frequency-doubled diode-pumped Nd:YAG master-oscillator power-amplifier laser system with programmable microsecond pulse length has been developed. Analog pulse shaping of the output from a single-frequency continuous-wave Nd:YAG oscillator, and subsequent amplification, allowed the generation of rectangular pulses with pulse lengths on the order of the Nd:YAG fluorescence lifetime. Temporally flat-top pulses of 1064 nm light with 520 mJ pulse energy, 2.6 kW peak power, and 200 $\mu$s duration, with linewidth below 10 kHz, were obtained at a repetition rate of 2 Hz. Second harmonic generation in a LBO crystal yielded pulses of 262 mJ and 1.3 kW peak power at 532 nm. The peak power can be maintained within 2.9% over the duration of the laser pulse, and long-term intensity stability of 1.1% was observed. The spatially flat-top beam at 1064 nm used in the amplifier is converted to a Gaussian beam at 532 nm with beam quality factor $M^2=1.41(14)$ during the second harmonic generation. This system has potential as a pump source for Ti:sapphire, dye, or optical parametric amplifiers to generate tunable high-power single-frequency radiation for applications in precision measurements and laser slowing.