In this paper, a photonic crystal structure composed of the silicon rods is proposed for an all-optical 4*2 encoder. Four input ports are connected to two outputs port via the cross-connections. Different radii of rods as defects are placed in the cross-connection region for coupling the optical waves from the input waveguides to the desired outputs. The total size of the device is about 133 μm2. Plane-wave expansion and finite difference time domain methods are used to calculate the band diagram and simulation of the optical wave propagation inside the structure, respectively. The maximum rise time of the device for all possible states is just about 205 fs which is less than one in the previous works. No need to a bias port and using the same power at input ports are other advantages of this work. The normalized output power margins for logic 0 and 1 are calculated by 2% and 34%, respectively. The simulation results demonstrate the presented structure is capable of using in optical integrated circuits.
- The maximum rise time of the device is just about 205 fs.
- The structure has no bias input signal.
- Difference between the logics is equal to 32%.