Specialty Yb fiber amplifier for microchip Nd laser: Towards approx1-mJ/1-ns output at kHz-range repetition rate

摘要

We demonstrate and optimize, for a mJs release at the wavelength 1.064 (mu)m, the operation of a compact laser system designed in the form of a hybrid, active-passive, Q-switched Nd~(3+):YAG/Cr~(4+):YAG microchip laser seeding an Yb-doped specialty multi-port fiber amplifier. As the result of the amplifier optimization, approx1 mJ, approx1 ns, almost single-mode pulses at a 1-10-kHz repetition rate are achieved, given by a gain factor of approx19 dB for an 11-(mu)J input from the microchip laser. Meanwhile, a lower pulse energy, approx120 (mu)J, but a much higher gain (approx25 dB) are eligible for the less powerful (0.35 (mu)J) input pulses.