Photonic crystal applications and their high performance lead them to be considered as a promising research area. The factors that affect their operation are the topology type, and the arrangement of its rod position, and their constructed materials. OR gate is proposed in this paper to be simulated and evaluated. This design is built on a square lattice- photonic crystal construction. Sensitivity analysis, and carefully rod locations are considered to obtain remarkable performance. Minimum size is the main property that distinguishes this design. Based on the simulations, a minimum size of 39.6 μm2 is obtained. The bit rate of 3.2 Tb/s is calculated for this structure. The considered threshold power level is 0.25. Comparison table is well organized for the recently published photonic crystal OR-gate that is based on ring resonator topology. Finite difference time domain and plane wave expansion method are used to analyze the proposed structure at 1.55μm wavelength to verify OR- gate operation. The fabrication methods are discussed and evaluated. As will be shown the size is decreased by around 23% of the recently published paper.