All-optical 1 × 2 decoder based on the self-collimated beam method in 2D photonic crystals

•All-optical 1 × 2 decoder based on 2D photonic crystals of Silicon rods in air is proposed.•Bit rate and contrast ratio of the device are 2.8 Tb/s and 2.02 dB, respectively.•Device is designed based on the self-collimation phenomenon.•PWE and 2D FDTD methods are utilized for the simulation of the structure.•Working wavelength of the device is 1.55 μm. The design, analysis, and simulation of a 1 × 2 decoder based on self-collimated beams was the aim of this work. The proposed structure consists of two-dimensional (2D) photonic crystals with their silicon rods in air. The device, of a relatively simple structure with a footprint of 228.71 μm2, comprises two inputs (I and Iref) and three outputs (Q1, Q2, and QI). It, furthermore, contains two beam splitters, produced by point defects. 2D Finite Difference Time Domain (FDTD) and Plane Wave Expansion (PWE) codes have been used for the simulation. Contrast ratio of 2.02 dB and a bit rate of 2.8 Tb/s were obtained for this device - potential candidate for all-optical digital integrated circuits.