The bond fluctuation model of superionic conductors proposed by one of the authors (MA) predicts that there must be a close relationship between the electronic polarizability and the ionic conduction in solids. Guided by this model, the relation between the nonlinear optical constants and the ion transport properties in crystalline and glassy ion conducting materials were studied previously. Those studies revealed that the nonlinear optical constant increases with the increase of the ionic conductivity. It was also noted that the optical properties could be also related with the structural relaxation. All these notions suggest the possibility that the optical properties of ionic conductors are interrelated with the mechanical properties of the materials. In the present study, such a possibility is investigated and corroborated using an anharmonic interatomic potential based theoretical model. Furthermore, it is shown that the previously found relation between the optical and the ionic transport properties can be understood analytically from the same interatomic potential point of view.