Similaritons: a new regime of femtosecond fiber lasers

We have recently demonstrated theoretically that similaritons can exist in a laser oscillator. Initial attempts to observe and exploit the self-similar regime of operation produced excellent results. A Yb-doped fiber laser designed to approximate the similariton regime produces the parabolic chirped pulses and unique sharp-edged spectrum that are the signatures of self-similar propagation. Optimum performance was obtained by slightly deviating from the self-similar regime, and 50-fs pulses with 5-nJ energy were generated after dechirping. These results represent twice the pulse energy, twice the average power, 5 times the peak power of the previous best femtosecond fiber lasers. In addition, the laser is probably the most efficient femtosecond laser: 240 mW output power is obtained with 500 mW of pump power.