Novel all-optical logic gates based photonic crystal waveguide using self imaging phenomena

All-optical logic gate with multifunctional performance have been designed theoretically in a two-dimensional photonic crystal waveguide (PCW) structure using multimode interference principle. A two dimensional finite-difference time domain (2D-FDTD) was employed in our numerical simulations. It is shown that by switching the optical signal to different input waveguide ports, the proposed device can function as XOR, OR, NOR and NOT gates simultaneously or individually. It is also shown that by a combination of photonic band gap and total internal reflection effects in PCWs, the device can operate for both, transverse electric (TE) and transverse magnetic (TM) polarizations. Our simulation results show that the optimized devices have very good transmission efficiencies, a broad frequency range and the contrast ratio are extending to high than 21 dB for TE and 17 dB for TM polarization. The total width and length of the devise are 2.16 and 8.20 respectively achieving miniaturization. It is a kind of promising device for next generation logic optical circuits, ultrahigh speed signal processing, and future photonic crystal based all-optical integrated circuits.