Journal of Electromagnetic Analysis and Applications, 2011, 3, 208-212 doi:10.4236/jemaa.2011.36034 Published Online June 2011 (http://www.SciRP.org/journal/jemaa) Copyright © 2011 SciRes. JEMAA Characterization and Optimization of Photonic Crystal Optical Power Limiters Igor Guryev, Igor Sukhoivanov, Edgar Alvarado Mendez, José Andrade Lucio Departament of Multidisciplinary Study, University of Guanajuato, Guanajuato, Mexico. Email: guryev@ieee.org Received March 6 th , 2011; revised April 1 st , 2011; accepted May 2 nd , 2011. ABSTRACT In the work, there have been investigated the optical power limiting effects which occur in the nonlinear photonic crys- tals possessing saturable Kerr nonlinearity. The method is proposed which allows exact determination of the parame- ters of the structure as well as the radiation parameters which provide the limiting effect. Keywords: Nonlinear Photonic Crystal , Optical Power Limiter , Kerr Nonlinearity 1. Introduction Today, one of important problems in optical commu- nications and information processing is development of effective optical power limiter on the basis of struc- tures with periodic modulation of refractive index. Such a problem is formulated, particularly, in [1]. Ear- lier, the utilization of nonlinear Cristiansen filters [2] as well as anisotropy induction in organic liquids [3] were proposed as optical power limiting devices. Par- ticularly, there are ideas based on the effect of appear- ance of Bragg grating at high level radiation intensity inside structures having initially uniform refractive index distribution [4]. Such devices are represented by some kind of layered structure with layers’ refractive indices initially equal. Layers are made of nonlinear materials with different nonlinearity coefficient so as the radiation intensity passing the structure increases, different variation of layers’ refractive indices appear. Due to this effect, the step-index (or any other periodic) structure appears. This can cause, at certain conditions, the limitation of optical radiation power at the output of such structure. In our work we investigated the possibility of the development of an optical power limiter based on the variation of reflectance spectrum of nonlinear PhC with Kerr-nonlinearity under the intense optical radiation. It is also given an analytical expression of necessary re- flectance spectrum form. Moreover, we made an ap- proximation of reflectance spectrum by the obtained analytical function and gave the parameters’ values for 1D and 2D PhCs. After this, the dependences of the output radiation intensity on the input one were given for these cases. Numerical results approve proposed theoretical model. 2. Theory The main function of an optical power limiter is to stabi- lize an intensity const I of an optical radiation. As an in- put data for this task there is the structure which reflec- tance depends on the radiation intensity. The task itself consists in the obtaining of the parameters of the struc- ture, the wavelength and the intensity range of the radia- tion that will provide the stabilization of the radiation intensity at certain level const I . Let’s represent const I as a radiation intensity passing the structure without absorption. At that const i I =I   i RI I   , where i I is the radiation intensity that inci- dents the structure. Thus, the passing radiation intensity will be incident intensity minus reflected intensity. This expression gives the dependence :  RI   1 i const const i i i I I I RI = = I I   (1) In the Figure 1 it is shown the set of curves for dif- ferent values of const I . By dashed lines it is shown the cross-point between the function and intensity axes. As it is seen, when the parameter const I varies, coordinate of the cross-point varies too as well as the slope of the func- tion. Thus, the variation of the reflectance in this way will result in the stabilization of the radiation intensity. It is now necessary to find the dependence of the re- flectance on the intensity for the case of nonlinear PhC