Interference based square lattice photonic crystal logic gates working with different wavelengths

• Interference based photonic crystal OR, XOR, NOT and AND optical logic gates are realized.
• For XOR and NOT gates the contrast ratio is more than 35 dB for particular wavelengths.
• All these logic gates are capable of operating with multiple wavelengths.
• The impact of radius on the operating wavelength and contrast ratio is analyzed.

We propose a new configuration of interference based OR, XOR, NOT and AND optical logic gates on a two dimensional square lattice photonic crystal (PhC) platform. The working of these devices was analyzed by the FDTD method and the operating frequency range was explored using the plane wave expansion method. The XOR and NOT gates have high contrast ratio which is more than 35 dB between high and low logic states, for a particular wavelength. All these devices are operating with multiple wavelengths. The impact of structural parameter like radius on the operating wavelength and Contrast Ratio (CR) was analyzed. It is found that the optimization of structural parameters makes it possible to obtain the operating wavelength allowed by band structure. These proposed devices were made up of linear waveguides and square ring resonator waveguides, without using nonlinear materials, optical amplifiers and external phase shifters.