All-fiber high-conversion-efficiency supercontinuum source based on photonic crystal fiber with low nonlinear coefficient

An all-fiber high-efficiency supercontinuum source based on photonic crystal fiber with low nonlinear coefficient was demonstrated. The pulse train with 5 ps duration, 20 MHz repetition rate, and 50 mW average power output from a mode locked fiber laser was amplified by a 15 μm-diameter large mode fiber amplifier. The output fiber of the amplifier was mode-matched to the photonic crystal fiber using two pieces of short fibers with narrower mode diameter. By pumping the 20 m long low nonlinear coefficient phontonic crystal fiber, a supercontinuum with wavelength extension over 650～1 700 nm was obtained. The output power of the generated supercontinuum was 670 mW pumped by 740 mW input amplified pulses, which implies a conversion efficiency over 90%. The supercontinuum generation process w