Nonlinearity and Dispersion Controlled All-Fiber High-Energy Femtosecond Chirped Pulse Amplification System with Peak Power More than 0.5 GW

A monolithic all-fiber high-energy chirped pulse amplification (CPA) system with a managed large dispersion is demonstrated. To lower the system’s nonlinearity, two temperature-tuning cascaded chirped fiber Bragg gratings (CFBGs) with a large dispersion of 200 ps/nm are used as the stretcher to stretch the pulse duration to more than 2 ns in the time domain. The main amplifier, a short-length silicate glass fiber with a large mode area and a high gain, increases the energy to 293 μJ at 100 kHz. To compress the large-dispersion chirped pulse into a compact structure, a reflective grating pair with a high density of 1740 lines/mm is used as the compressor. Owing to the high-order dispersion pre-compensation by the CFBGs and the large-sized grating with high diffraction efficiency, a compressed pulse duration of 466 fs with a pulse energy of 250 μJ is obtained, corresponding to a compression efficiency of more than 85%. The well-preserved beam quality with measured M2 value is better than 1.3. To best of our knowledge, this is the highest pulse energy ever achieved in a monolithic fiber femtosecond laser system.