We have designed an ytterbium rod-type fiber laser oscillator with tunable pulse duration. This system that delivers more than 10 W of average power is self mode-locked. It yields femtosecond to picosecond laser pulses at a repetition rate of 74 MHz. The pulse duration is adjusted by changing the spectral width of a band pass filter that is inserted in the laser cavity. Using volume Bragg gratings of 0.9 nm and 0.07 nm spectrum bandwidth, this oscillator delivers nearly Fourier limited 2.8 ps and 18.5 ps pulses, respectively. With a 4 nm interference filter, one obtains picosecond pulses that have been externally dechirped down to 130 fs.

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We have developed a high power high efficiency picosecond laser system delivering up to 2MW Peak Power at 1030nm for various pulse durations from 15ps to 50ps. The laser is based on the direct amplification, with Large Pitch Rod-Type Fibers, of a Mode Locked Fiber Laser and can deliver up to 100µJ energy at 50ps with excellent beam quality (M²<1.2) and reasonable non-linear effects. We demonstrated 95W output power at 1030nm for 165W of pump power and performed harmonic generation leading to 48W at 515nm and 21W at 343nm.