Development of Virtual Optical Waveguide: Effect of Flatness Ratio of Open Elliptical on High-Pressure Area by 3D Numerical Calculation

In this paper, we propose to form a virtual optical waveguide with a focused underwater shock wave. The region where the shock wave is focused becomes high pressure and high density. In other words, a localized high-refractive index region is obtained. Increasing the pressure gradient generated by focusing shock wave, light can be confined within the refractive index region and propagate without leakage. We investigated the optimal number of divisions for 3D-Gaussian pressure distribution to model a high-pressure region generated by laser irradiation. Also, we discussed the effects of the flatness ratio of the open elliptical reflector on the focusing behavior of underwater shock wave by 3D Numerical calculation. In the calculation, the axisymmetric 3D unsteady compressible ALE (Arbitrary Lagrangian–Eulerian) and the Mie-Grüneisen equation of state were solved using the finite volume method. As a result, it was determined that three divisions Gaussian pressure distribution is optimal for modeling the high-pressure area generated by laser irradiation. Furthermore, it was confirmed that the flatness ratio decreased, the shock wave becomes more focused around the focal point.