1975 nm linearly-polarized MOFA CPA system based on CFBG stretcher and 1+3-pass CVBG compressor configuration

The 2 μm spectral region is useful for applications in processing of semiconductors and clear polymers, and also interactions with water-rich biological tissues and biomaterials [1]. Fiber laser sources are attractive as 2 μm sources as they offer excellent beam quality, and the ability to dissipate heat along long fiber lengths enabling high output power. However, amplification of pulses with high peak power is limited by nonlinear effects due to the small mode area. Chirped pulse amplification (CPA) technique allows amplification of high energy pulses by first stretching the pulse - chirping - to minimize nonlinear effects [2]. The amplified pulse is then compressed using dispersion compensation elements such as diffraction gratings. However, when the pulse is chirped to long durations in the scale of hundreds of picoseconds or longer, diffraction gratings require distances of a few meters which negates the compactness of fiber laser systems.