Long-pulse, single-frequency 1064 nm laser and frequency doubling

Abstract

An all-solid-state single-frequency 1064 nm laser with a 100 µs pulse width, 500 Hz repetition rate and 700 mJ single pulse energy is designed using seed injection and a three-stage master oscillator power amplifier (MOPA) construction. Using this as a basis, research on long-pulse laser frequency doubling is carried out. By designing and optimizing the lithium triborate (LBO) crystal, the theoretically calculated maximum conversion efficiency η max reaches 68% at M 2 = 1, while η min is 33% at M 2 = 3. Generation of 212 mJ pulses of green light with a repetition rate as high as 500 Hz is obtained from a fundamental energy of 700 mJ. The experimental conversion efficiency reaches 31% and the power stability is better than ±1%.

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

“…In combination with an acousto-optic modulator for pulse shaping of the cw master oscillator output, this enabled the generation of rectangular time-profile pulses with widths on the timescale of the fluorescence lifetime of the amplification medium. The single-frequency output with < 10 kHz linewidth, excellent beam quality in the second harmonic, and stable, high peak powers realized here using a compact 2-stage amplification setup compares favorably to other, previously demonstrated systems [7][8][9][10][11][12][13].…”

“…This may enable the amplification of low power tunable lasers in a gain medium like titanium:sapphire, or via optical parametric processes. Compared to existing systems, we combine pulse shaping capabilities [6,7] with pulse durations on the order of 100 microseconds [8][9][10][11][12][13], while avoiding spikes and ensuring a flat rectangular temporal profile. The spatial flat-top beam profile is maintained throughout the laser system using relay lenses (not shown) with the image planes indicated in green.…”

A 37 mJ, 100 Hz, high energy single frequency oscillator*

“…[31][32][33][34][35][36][37][38][39][40][41][42][43] For energy enhancement, a master-oscillator power-amplifier is a well-established technique. [44][45][46][47][48][49][50][51][52] Isyanova reported a 55 mJ single-frequency laser by a MOPA system, and the oscillator has the energy of 0.8 mJ with inserted etalon. [47] Tong reported 101 mJ single-longitudinal-mode Nd:YAG laser by a pre-amplifier and amplifier system and the oscillator has an energy of 1.25 mJ obtained by a short cavity with inserted etalon.…”

“…The 10 mW single-frequency CW oscillator is amplified to 0.7 W by a fiber amplifier and to 350 W (700 mJ/pulse) by the MOPA system, it is a powerful amplifier with amplifying ability of 3.4 ⊆ 10 4 times. [52] The MOPA investigation shows attractive potential for energy/power scaling and it makes the principal validation viable. The problem is that the MOPA system is too complex and huge for application, as the pulse energy of oscillators is limited to several milli-Joule levels now.…”