Simulations of optical switching effects of a guided-mode resonant grating filter with a Kerr medium

We propose an optical switch of a guided-mode resonant grating (GMRG) filter with a Kerr medium and simulate optical switching effects by using the nonlinear finite differential time domain (FDTD) method. It is shown that the nonlinear FDTD method is needed for simulating the optical switch effect by analyzing the bistable feature. The doubly periodic structure was used in order to produce the optical Kerr effect efficiently. Because a doubly periodic GMRG filter operates for small beam diameter and grating area, the electric field can be accumulated to the small area. The doubly periodic grating consisted of materials with refractive indices of 1.88 and 1.0, and the material of index 1.88 had a third-order susceptibility of 8.5×10 -10 esu. The TE polarized plane waves were normally incident on the grating structure as “pump light” and “probe light.” When the intensity of “pump light” increases, the refractive index changes due to the optical Kerr effect, so that the resonant condition of the GMRG filter for the “probe light” also changes. Therefore the transmittance of “probe light” can be controlled by the “pump light.” By changing “pump light” from 0 to 100kW/mm 2 , the transmittance of “probe light” was controllable from 0 to 0.6.