Modeling of a dual-wavelength fiber amplification system for further mid-infrared generation

Abstract A dual-wavelength, two-stage Yb-doped fiber amplification system is theoretically studied for further mid-infrared generation. In this amplification system, two sections of double-clad single-mode Yb-doped fiber are used as the gain medium, and the spectrum in the wavelength range 1000–1120 nm is simulated. For the simulation of the preamplification stage, a 975 nm diode laser with a power of 6.5 W is used to pump the preamplification stage by the counter-pumping scheme, and the measured dual-wavelength seed spectra are used. For the main amplification stage simulation, the gain fiber length is 1.7 m, and a 975 nm, 7.5 W diode laser is used as the pump source. Results show that for the two-stage amplification process, the maximum value of the dual-wavelength power product can be obtained in the main amplification stage with a 1.7 m gain fiber when the 2.2 m Yb-doped fiber is selected for the preamplification stage with the counter-pumping scheme. Under the above condition, the total average power of the seed signal after amplification is calculated to be 3.2 W, with negligible ASE noise. In addition, we have compared the theoretically calculated spectral results with the experimental results of the actual main amplification stage.