In this paper, we are going to employ seven optical waveguides (OWGs) based on two-dimensional (2D) linear photonic crystal (LPhC) for realizing an all optical comparator (AOCMP). The proposed 1-bit AOCMP has a very simple structure with a footprint of 351 μm 2 which is composed of 31 × 33 cubic lattice of silicon rods immersed in air. This LPhC comparator comprises two input ports and two output ports. The functionality of the proposed 1-bit AOCMP is based on constructive and destructive interference phenomenon of optical beams and phase shift keying technique. The nite difference time domain (FDTD) procedure based on Yee's Algorithm is used to compute the propagation of optical waves in this structure. The FDTD simulation results of suggested 1-bit AOCMP indicate that the minimum and maximum values of the normalized power (NP) at ON and OFF states for output ports are 73% and 15%, respectively. Also, the ON-OFF contrast ratio (CR), bit rate (BR), rise and fall times (T r and T f ) of the suggested design are about 6.87 dB, 2.22 Tb/S, 0.15ps and 0.05ps, respectively.