MOPA with high-gain solid-state amplifier

摘要

Radiation from a VBG-locked diode-laser at a locked wavelength of 878.6 nm is focused into a 30-mm long Nd:YVO4 optical amplifier crystal for optically pumping the crystal (24). The crystal amplifies a beam of seed-pulses from a fiber MOPA (12). The power of pump radiation is about 75 Watts. The radiation is focused into a beam-waist having a minimum diameter of about 600 micrometers. This provides an amplifier having a high gain-factor well over 100. The high-gain factor provides a gain-shaping effect on the seed-pulse beam which overcomes thermal aberrations inherent in such high-power pumping, thereby producing an amplified seed-pulse beam with M2 less than 1.3.

主权项

1. Laser master oscillator power amplifier apparatus, comprising:
a source of seed-pulses having a duration between about 1 picosecond and about 30 picoseconds and a pulse-energy between about 0.5 and 5 nanojoules the seed-pulses characterized as having a seed-pulse beam; a neodymium-doped yttrium vanadate crystal for amplifying the seed-pulses, the crystal having a crystal length and an entrance face and an exit face, and the seed-pulse beam entering the crystal via the entrance-face and exiting the crystal via the exit-face and having a diameter which is about constant within the crystal; a source of CW optical pump-radiation having a wavelength of about 878.6 nanometers; at least one optical element arranged to focus the pump-radiation into a beam-waist coaxial with the seed-pulse beam, the beam-waist having a minimum diameter about at the entrance face of the crystal, and the beam-waist having a beam waist-length defined as the distance between points on opposite sides of the minimum diameter where the beam waist-length is about 1.414 times the minimum diameter; and wherein the neodymium-doped yttrium vanadate crystal has a neodymium-doping concentration between about 0.12% and 0.2%, the pump-beam has a diameter between about 1 and 1.5-times the seed-pulse beam diameter at the entrance-face of the crystal and greater than or equal to about three-times the seed-pulse beam diameter at the exit face of the crystal, and the CW pump-radiation has a power about equal to or greater than about 50 Watts.