A two-pump fiber optical parametric amplifier (FOPA) based on the photonic crystal fiber (PCF) with As<sub>2</sub>S<sub>3</sub> background in the mid-infrared (MIR) region is investigated numerically. The genetic algorithms are used to optimize the gain of the FOPA, and the amplifier peak gain, bandwidth and flatness are investigated in detail for the variety of the fiber length, the input signal and pump power. In addition, the comparison of the gain spectra between considering and neglecting the loss of the PCF is given. The results show that the wideband gain spectra with high peak gain can be obtained by using a short length of the PCF with the relatively low pump power, which show the great potential of the FOPA at wavelengths in the MIR region.
In this paper we numerically investigate the effect of the reverse cross-relaxation process on the inversion population of laser levels in Tm-doped glass based active system. We show the impact may be significant when high inversion population is required.