Abstract: Photonic Crystals (PCS), an analog of semiconductors for light waves, are composite periodic dielectric materials that provide novel and unique ways control many aspects of electromagnetic radiation. Harnessing the nonlinear properties of PCS offers an opportunity to create the all-optical devices. It is shown that the optical Kerr effect taking place in third order can be used effectively to obtain an ultra compact switch controlled by the intensity of a pump signal. Since the switching relies on the geometry of the 2DPC, it becomes possible to use highly nonlinear materials. The aim of this contribution is to demonstrate a highly efficient directional coupler based on the triangular lattice of circular Kerr-nonlinear dielectric rods suspended in air. We demonstrate, through a main body of the Finite Difference Time Domain (FDTD) algorithm for the third order nonlinearities the feasibility of all-optical switching in the improve structure. This study show that is possible to obtain an efficient all-optical switcher with few means and less expenses, we also compare the potentials of different photonic crystal lattices for designing single-mode waveguide and conclude that triangular structures are the best choice.