A novel all optical reversible 4 × 2 encoder based on photonic crystals

In this paper, we designed a reversible all-optical 4 × 2 encoder using a two-dimensional square lattice rods in air photonic crystal with nonlinear refractive index. Our main structure composed of seven vertical waveguide and two elliptical rings. Plane Wave Expansion (PWE) and Finite Difference Time Domain (FDTD) methods are used to calculate band structure and wave propagation in the structure, respectively. Reversible encoder is designed within small size and has ability to be integrated in optical integrated circuits. This reversible encoder is the first optical encoder based on photonic crystals. The results show that our structure could act as an optical reversible encoder.