Femtosecond laser system based on thin rod active Yb : YAG elements with high average output power and pulse energy

A three-stage laser amplifier system based on thin Yb : YAG rods with laser diode pumping has been developed and manufactured. A continuous train of femtosecond pulses from an Yb : KGW master oscillator with a repetition rate of 80 MHz and an initial duration of 150 fs is controlled by a Pockels cell to a frequency of 0.25–1 MHz and is amplified in the system by more than 6500 times to an average power of over 100 W. To suppress self-focusing, the pulses are lengthened in a stretcher on a volume Bragg diffraction grating, amplified, and then compressed to 947 fs. The energy of femtosecond pulses compressed after amplification exceeds 100–170 μJ at different repetition rates, which makes it possible to use them for efficient micromachining of various materials.