en 2-Optoelectronics and Photonics Optoelectronics and Photonics Research Paper Research Paper We report the simulation results for impact of nonlinear Kerr effect on band structures of a ‎two dimensional photonic crystal (2D-PhC) with no defect, a PhC based W1-waveguide ‎‎(W1W), and also Coupled-Cavity Waveguides (CCWs). All PhC structres are assumed to a ‎square lattice of constant a made of GaAs rods of radius r=0.2a, in an air background. The ‎numerical simulation was performed using the nonlinear finite difference time domain ‎‎(NFDTD) technique. To study the impact of Kerr effect on the photonic band structures, E-‎polarized lights of peak input intensities 0.5 GW-cm−2≤I≤25 GW-cm−2 have been used. The ‎numerical results have shown that as the input light intensity increases, the band edges for all ‎PhC waveguide structures considered experience red shifts. These numerical results for CCWs ‎also show that the larger the light input intensity, the smaller is the corresponding maximum ‎light group velocity.‎ Photonic Crystal (PhC),Nonlinear Kerr Effect,Photonic Band Structures,Dispersion Curve,Waveguides, 122 130 http://ijeee.iust.ac.ir/browse.php?a_code=A-10-373-2&slc_lang=en&sid=1 A. Khodabakhsh amir.khodabakhsh@gmail.com 180031947532846002404 180031947532846002404 No TARBIAT MODARES UNIVERSITY M. K. Moravvej-Farshi farshi_k@modares.ac.ir 180031947532846002405 180031947532846002405 Yes TARBIAT MODARES UNIVERSITY M. Ebnali-Heidari Ebnali-m@eng.sku.ac.ir 180031947532846002406 180031947532846002406 No Sharekord University