Generation of 2-mu J 410-fs pulses from a single-mode chirped-pulse fiber laser operating at 1550 nm

We report on a simple, robust, femtosecond chirped-pulse-amplification system, based on Er-and Er-Yb-doped fibers, operating at a central wavelength of 1555 nm. The entire system is constructed from commercially available fiber components, except the grating compressor, for easy duplication by other researchers. The laser system produces chirped pulses with up to 4 mu J of pulse energy at 250 kHz. After dechirping, the pulse duration is 410 fs and the pulse energy is reduced to 2 mu J. The repetition rate of the laser is electronically tunable between 125 kHz and 60 MHz, limited by strong amplified spontaneous emission (ASE) generation at the low end. The amplifier system is almost completely fiber integrated, except for the pump delivery into the final amplifier stage, which is free-space backward-pumped to reduce undesired nonlinear effects, and the compressor which was designed using the gratings. The laser is practically free of misalignment and has exhibited excellent long-term stability during its use in various experiments for more than 600 working hours.