Controlling Band Gap of One Dimensional Photonic Crystals via the Nonlinear Characteristic of Layers

In this paper, band structure of one-dimensional photonic crystal consisting of two-layer dielectrics is calculated (The first layer is the vacuum and the second layer is ZnSe). Then, the photonic crystal band structure by- nonlinear characteristics of layers and different intensity radiation values -is calculated. The refractive index modification is applied for each layer and its effect on the electrical permittivity coefficients is calculated. Since the transmission and reflection coefficients of photonic crystal depends on the layer electrical permittivity, the band structure of crystal changes as the layer electrical permittivity change. The results show that by increasing the light radiation intensity, the frequency of the band gap branches decreases, therefore in TE and TM polarizations band gap branches shift slightly to lower frequencies. In addition it is shown that new band gap branches appeared at higher frequencies which indicates that crystal band structure can be controlled by the intensity of the radiation field. In order to demonstrate the practical ability of nonlinear optics, the band structure of photonic crystal is calculated in both regimes (linear and nonlinear optics) and compared with each other. These structures can be used as anti-reflective coatings that reduce reflections from the surface. In fact, by covering war devices with band gap controllable nonlinear optical photonic crystals, they can be hidden from the enemy's radar view.