Numerical Simulation of Q-Switched Supersonic Flow Chemical Oxygen-Iodine Laser by Solving Time-Dependent Paraxial Wave Equation

The quality and power of an extracted beam from a Q-switched supersonic flow chemical oxygen-iodine laser have been investigated by numerical simulation. The flow system adopted in this study is the throat-mixing system proposed in a previous paper. Three-dimensional calculation for optics is coupled with one-dimensional calculation for gas flow including chemical reactions. Both geometric and wave optics are calculated and compared to assess the effects of diffraction. Wave optics is calculated with a time-dependent paraxial wave equation. The results indicate that wave and geometric optics are qualitatively similar in the time-dependent behavior of beam power. Quantitatively, it is found that diffraction reduces the extracted power by 9%. It is also found from the spreading half-angle of the beam for wave optics that the beam quality at a maximum power is equivalent to that of a plane wave; however, it is lower than that of continuous extraction.