In this work, an all-optical half adder is proposed based on a two-dimensional photonic crystal with uniform structural parameters. The proposed structure is composed of a triangular lattice of dielectric rods in air. The structure has been designed based on interference of light in waveguides which are formed by removing a number of dielectric rods. The structure has been simulated by using the plane wave expansion and the finite difference time domain methods. The size of the proposed structure is small with dimensions of 17 μm × 12.2 μm. The structural parameters such as radius of dielectric rods and dielectric constant are uniform across the structure, which makes it easier to fabricate with less fabrication errors. The proposed structure does not need high input power, and it has a fast response time.