Abstract
130-W average-power picosecond green laser pulses at 514.5 nm are generated from a frequency-doubled hybrid cryogenic Yb:YAG laser. A second-harmonic conversion efficiency of 54% is achieved with a 15-mm-long noncritically phase-matched lithium triborate (LBO) crystal from a 240-W 8-ps 78-MHz pulse train at 1029 nm. The high-average-power hybrid laser system consists of a picosecond fiber chirped-pulse amplification seed source and a cryogenically-cooled double-pass Yb:YAG amplifier. The M(2) value of 2.7, measured at 77 W of second-harmonic power, demonstrates a good focusing quality. A thermal analysis shows that the longitudinal temperature gradient can be the main limiting factor in the second-harmonic efficiency. To our best knowledge, this is the highest-average-power green laser source generating picosecond pulses.
Highlights
High-average-power pulsed green lasers have been widely used for both scientific and industrial applications, such as pumping near-infrared ultrashort high-power lasers, laser machining, and laser material processing
130-W average-power picosecond green laser pulses at 514.5 nm are generated from a frequency-doubled hybrid cryogenic Yb:YAG laser
The high-average-power hybrid laser system consists of a picosecond fiber chirped-pulse amplification seed source and a cryogenically-cooled double-pass Yb:YAG amplifier
Summary
High-average-power pulsed green lasers have been widely used for both scientific and industrial applications, such as pumping near-infrared (near-IR) ultrashort high-power lasers, laser machining, and laser material processing. Intra-cavity frequency-doubled Q-switched nanosecond Nd-doped lasers have been one of the most popular green lasers and average power levels of >300 W have been demonstrated with this technology [1] This type of green laser has been the main workhorse for ultrashort pulse high-power laser technology, as a pump source for femtosecond Ti:sapphire laser amplifiers at various repetition rates [2,3,4], as well as its direct use in industrial laser-machining technology, such as marking, welding, and cleaning. A high-beam-quality nanosecond green laser with an average power of 103 W was demonstrated from an external-cavity frequency-doubled Nd:YVO4 master oscillator-power amplifier (MOPA) system [6]. We will describe the configuration of our laser system, the phase matching property of the LBO crystal, and the experimental results achieved, along with discussions
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