On the optical bistability of ferroelectrics via two-wave mixing: Beyond the slowly varying envelope approximation

In this paper, we investigate the Optical Bistability (OB) resulting from a degenerate two-wave mixing process in a single layer of Kerr nonlinear ferroelectric material. The nonlinear process is mathematically described by a nonlinear coupled-wave (CW) equations propagating across the nonlinear medium. The system is solved numerically with and without employing the Slowly Varying Envelope Approximation (SVEA). The effects of layer thickness, operating frequency, and the intensity of the probe beam on the bistable response are investigated in both cases with and without SVEA. We have found that there is a significant difference between both solutions (with and without SVEA) in the analysis of the CW theory of two-wave mixing for OB. The SVEA solution fails to predict the bistable response for various combinations of the input parameters. Furthermore, the solution with SVEA overlooks the detection of several bistable response periods, reduces the switching contrast of the detected OB, and shows only higher threshold values of bistable response. A comparison between our theoretical results and some available experimental data is also shown.