Nonlinear compression of Q-switched laser pulses to the realm of ultrashort durations

Mode-locked lasers have an undisputed position in the ultrafast domain, though they are fairly expensive for miscellaneous applications. Thus, laser consumers revert to more cost-effective systems like Q-switched lasers. Here we report on the nonlinear compression of passively Q-switched laser pulses that allows accessing the time domain of sub-10-picoseconds, which has been so far the realm of mode-locked lasers. Laser pulses with an initial duration of 100 ps from a passively Q-switched microchip laser are amplified in a photonic crystal fiber and spectrally broadened from 20 pm to 0.68 nm by self-phase modulation. These pulses are compressed in a grating compressor to a duration of 6 ps with a pulse energy of 13 µJ.