Realization of an All-Optical Ultra-Fast and Compact Reversible Feynman Logic Gate

We present a photonic-crystal structure for a reversible Feynman logic gate to be used in all-optical processors. The proposed structure consists of GaAs dielectric rods in the air. We use the plane-wave expansion (PWE) and finite-difference time-domain (FDTD) methods to examine the proper operation of the photonic-crystal logic gate. An important advantage of reversible logic gates is the ability to access logic gate inputs, using logic gate outputs. The use of these logic gates in photonic-crystal structures leads to high speed in calculations. This structure provides an ultra-fast and ultra-compact logic gate with a response time of 0.8 ps and a size of 78.34 μm2. In addition to the ultra-compactness of this logic gate, achieving an appropriate contrast ratio is the other advantage of the proposed photonic-crystal logic gate. The minimum contrast ratio of the structure is obtained to be 11.8 dB. Maintaining the efficiency of the device is the other critical subject of research. In addition to its usage as a reversible logic gate, this structure may also be multifunctional for alternative purposes, including XOR, comparator, buffer, and NOT logic gates in all-optical processors.