Abstract-In this letter, the 1 × 3 power splitter with square lattice configuration is numerically investigated using 2-D finite difference time domain simulation. The device is presented and compared with its counterparts in triangular lattice. It is found that efficient total transmission of about 86%, at output ports are obtained around the optical operating wavelength 1.55 μm. The simulation results confirm that the 1 × 3 splitter in square lattice can't provide an efficient splitting over a broad bandwidth in comparison with the triangular lattice.Index Terms-Two-dimensional photonic crystals, 2D-FDTD method, 1 × 3 splitter, square lattice, power splitter, optimization.