Design of an ultra-compact photonic crystal based all optical XOR and NOT logic gates.

Photonic crystals are periodic structures that are suitable for designing a variety of optical gates and logic circuits. In this paper, XOR and NOT logic gates are designed using two-dimensional square lattice photonic crystals. This structure consists of two inputs and one output, and the logical values ​​in the inputs and outputs are defined based on the amount of optical power. The plane wave expansion (PWE) method has been used in band structure calculations. The simulation results show that the proposed structure in a range of wavelengths has a photonic band gap that has a wavelength of 1.55 µm in this range. Therefore, the light sources placed in the inputs have a wavelength of 1.55 µm. Due to the use of a square structure that is easier to design and build, this structure is suitable for use in optically integrated circuits. Another advantage of this structure, in addition to its small dimensions, is the very low value of zero logic, which has increased the contrast ratio in the structure. The contrast ratio obtained in this structure is equal to 19.1 dB. [ABSTRACT FROM AUTHOR]