Broadband, Continuous-Wave, Mid-Infrared Generation Based on ASE Fiber Source

The research reports broadband, continuous-wave (CW), mid-infrared generation based on an optical parametric oscillator (OPO), pumped by an amplified spontaneous emission (ASE) fiber source. The ASE fiber source has a ytterbium (Yb)-doped fiber master oscillator power amplifier (MOPA) structure. By injecting another fiber laser with high power and a narrow linewidth into the nonlinear crystal, the phase-matching difference frequency generation (DFG) can be realized at a low pumping threshold. It is shown that during the down-conversion of the ASE fiber source, the intracavity DFG can steadily and effectively generate a broadband mid-infrared laser, with a central wavelength of 3713 nm. The bandwidth of the mid-infrared laser is 122 nm. The pump power of 2 W generates a 0.238 W mid-infrared laser with a pump-idler conversion efficiency of 11.6%. It has tremendous application potential in the research of broadband CW mid-infrared lasers.