Picosecond laser with 11 W output power at 1342 nm based on composite multiple doping level Nd:YVO4 crystal

• Robust long-lasting passively mode-locked 1342 nm 12.5 ps Nd:YVO4 seeder was developed.
• Nd:YVO4 regenerative amplifier running at 300 kHz is optimized for 1342 nm wavelength.
• 11 W average power and 2.8 MW peak power achieved from ~13 ps DPSS MOPA at 1342 nm.
• Composite multiply Nd doped YVO4 rod pumped with 70 W at 880 nm ensures M2<1.1.
• High repetition rate ps laser for selective micromachining at 1342 nm was developed

We report results of design and optimization of high average output power picosecond and nanosecond laser operating at 1342 nm wavelength. Developed for selective micromachining, this DPSS laser is comprised of master oscillator, regenerative amplifier and output pulse control module. Passively mode-locked by means of semiconductor saturable absorber mirror and pumped with 808 nm wavelength Nd:YVO4 master oscillator emits 12.5 ps pulses at repetition rate of 55 MHz with average output power of ∼100 mW. The four-pass confocal delay line forms a longest part of the oscillator cavity in order to suppress thermo-mechanical misalignment. Picked from the train seed pulses were injected to the cavity of regenerative amplifier based on composite Nd:YVO4 crystal with diffusion-bonded segments of multiple Nd doping concentration end-pumped at 880 nm wavelength. Laser produces pulses of ∼13 ps duration at 300 kHz repetition rate with average output power of 11 W and nearly diffraction limited beam quality of M2∼1.03. Attained high peak power ∼2.8 MW facilitates conversion to the 2nd, 3rd and 6th harmonics at 671 nm, 447 nm and 224 nm wavelengths with 80%, 50% and 15% efficiency respectively. Without seeding the regenerative amplifier transforms to electro-optically cavity-dumped Q-switched laser providing 10 ns output pulses at high repetition rates with beam propagation factor of M2∼1.06.