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

Abstract

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.