A Compact High-Average-Power Femtosecond Fiber-Coupled Two-Color CPA System

A compact, high-average-power, sub-picosecond, two-color (1025 and 1085 nm) fiber-coupled, chirped pulse amplification Yb:fiber laser is reported. Two colors are selected from a continuum using a chirped fiber Bragg grating, which are then amplified in a two-stage Yb:fiber amplifier system. The preamplifier is fully fiber-coupled, improving significantly the stability and efficiency compared to the former bulk-optic system. The system delivers two-color pulses with the total average power of 2.3 W (1.9 W at 1025 nm and 0.4 W at 1085 nm) at a 65 MHz repetition rate. The FWHM duration of the final compressed output pulses of each color is 900 and 600 fs. The amplified spectrum showed insignificant spontaneous emission between the colors, indicating that the separation could be further increased.