An optimized all-optical "NAND" logic gate is studied analytically. The particular characteristic of this logic gate is that it is based on photonic crystals, it consists of a resonator coupled with two waveguides on a silicon substrate. The operating wavelength is equal to 1.55µm which represents the telecommunication wavelength, the switching power of the optical logic gate studied is 1.693 kw /µm2 its response is independent of the response of the resonator when the power intensity of the optical waves is lower than the resonance wavelength, the light will be coupled in the waveguides, in the opposite case the light propagates in the waveguide of the bus.

A new connected structure of an all-optical “OR” logic gate realized with photonic crystals is proposed in this study. The structure is based on coupling the input guides with two microcavities; the unit cell of the structure is designed to achieve a band gap around the communication wavelength (i.e., 1.55 µm). The performance of the structure results in transmission efficiency and low losses. This compact size logic gate is considered an important element in the integration of a nanoscale photonic device.

We propose the optimization of a micro-component for the integrated optics which is the AND logic gate formed by a Y-junction based on two-dimensional crystal Photonics with a triangular lattice of air holes in silicon. We chose this structure to improve the transmission of single mode with high power and low losses compared to the AND logic gate classic, by optimizing the photonic crystal geometric parameters, the band gaps wavelength and eliminate the higher order modes in order to realize an optimized AND logic gate.