Shiguang Li

Double-pulse single-longitudinal-mode operation of injection-seeded laser using intracavity phase modulator

A single-longitudinal-mode (SLM) double-pulse injection-seeded neodymium-doped yttrium aluminium garnet (Nd:YAG) laser was established utilizing an RbTiOPO4 electro-optic crystal to modulate the optical path of the slave resonator for generating a resonance condition. The Q-switcher was fired twice during every pump period. This enabled the laser to emit a pair of SLM laser pulses with a time separation of 200 mu s. Each pulse had a pulse energy of 13 mJ at 50-Hz repetition rate, pulse duration of 20 +/- 0.5 ns, and linewidth of 30 +/- 0.3 MHz (within 2 min). The beam quality factor of M-2 was <1.22. A frequency jitter of 1.4 MHz was obtained within 2 min

High efficiency single frequency 355 nm all-solid-state UV laser

A novel conductively cooled high energy single-frequency 355 nm all-solid-state UV laser is presented based on sum-frequency mixing technique. In this system, a pulsed seeder laser at 1064 nm wavelength, modulated by an AOM, is directly amplified by the cascaded multi-stage hybrid laser amplifiers, and two LBO crystals are used for the SHG and SFG, finally a maximum UV pulse energy of 226 mJ at 355 nm wavelength is achieved with frequency-tripled conversion efficiency as high as 55%, the pulse width is around 12.2 ns at the repetition frequency of 30 Hz. The beam quality factor M-2 of the output UV laser is measured to be 2.54 and 2.98 respectively in two orthogonal directions.

1KHz high average power single-frequency Nd:YAG laser

A laser-diode-pumped master oscillator and power amplifier was developed with high efficiency, high average power and high beam quality. The oscillator is an injection-seeding, fiber coupled diode-end-pumped E-O Q-switched Nd:YAG laser, producing single frequency pulse laser output with pulse energy of 8mJ and pulse width of 11ns at a pulse repetition rate of 1KHz，The 1KHz was divided into four chains with frequency of 250Hz, through E-O modulation technology, The power amplifier utilizes conductively-cooling Nd:YAG zigzag slab with two sides’ pump architecture at bounce point. Pulse energy of more than 800mJ with pulse widths of 12.6ns was obtained at repetition rate of 250Hz in every amplifier chain, the frequency-doubled pulse energy of 360mJ when KTP crystal was used was obtained at a repetition of 250Hz.

Optical parametric amplifier at 1572nm wavelength using KTiOAsO4 crystal

We report on a nanosecond master oscillator /power amplifier architecture for optical parametric conversion of high pulse energy from 1.064μm to 1.572 μm in KTiOAsO4 crystal. The signal emission is amplified by two different parametric amplifier architectures respectively. By comparing the results obtained, a novel amplifier architecture is chosen which is expected to combine the high gain and good beam quality. With a seeding signal energy of 1 mJ, and 400mJ pump pulse at 100Hz, a gain up to 64 at 1.57μm with the beam quality M2 less than 4.8 is realized. The total optical-optical conversion efficiency reached 16%.