Large-Mode-Area Er-Doped Fiber Chirped-Pulse Amplification System For High-Energy Sub-Picosecond Pulses At 1.55 Mu M

We demonstrate a chirped-pulse amplification system generating 25 mu J compressed pulses at a center wavelength of 1552.5 nm. The seed module and the amplifier chain are all in-fiber (with a few small fiber-pigtailed free-space components), followed by a free-space diffraction grating pulse compressor. The amplifier chain contains a pre-amplifier and a booster whose gain fibers are 45/125 mu m core/cladding-diameter, core-pumped Er-doped fibers. The pump lasers for both amplifiers are single-mode 1480 nm Raman lasers capable of up to 8 W output. The seed module generates up to 2 ns chirped pulses that are amplified and subsequently compressed to < 800 fs duration. At a repetition rate of 50 kHz, the 2 ns pulses from the seed module were amplified to 72 mu J, resulting in 25 mu J after pulse compression. The corresponding peak power levels after the amplifier chain and compressor were 36 kW and 31 MW, respectively.