This paper presents a triangular lattice of two-dimensional photonic crystal in the design of a novel all-optical 1×2 decoder. To control and conduct light, linear and point defects were developed in curved directions. In addition to the main entrance, a controlling entrance was assumed to control light using light interference theory when the input source is active and to activate the intended output in its absence. Logical values of “0” and “1” are introduced based on the ratio of output-to-input power. Plane wave expansion is used to calculate band structure of the lattice and the finite difference time domain method is used to calculate the optical power distribution in waveguide paths. The key feature of the proposed structure are low size and contrast enhancement, which will reduce the error in the decoder output. The results show that the structure can be used as a decoder with a bit rate of about 2 Tbit/s and time delay of 0.1 ps.
