A Novel Design for an All-Optical Half Adder Using Linear Defects in Photonic Crystal Microstructure

This paper reports a new optical half-adder design using linear defects in a photonic crystal (PhC) structure. The half adder's proper design obviates the need to increase the input signal's intensity for the nonlinear optical Kerr effect's appearance, which leads to the diversion of the incoming light toward the desired output. The proposed device is composed of silicon rods consisting of four optical waveguides and a defect in a PhC. Two well-known plane wave expansion and finite difference time domain methods are used to study and analyze photonic band structure and light propagation inside the PhC, respectively. The numerical results demonstrate that the ON-OFF contrast ratios are ۱۶ dB for “Sum” and about ۱۴ dB for "Carry".  They also reveal that the proposed half-adder has a maximum time delay of ۰.۸ ps with a total footprint of ۱۵۸ µm۲. Due to very low delay time, high contrast ratio, and small footprint, they are more crucial in modern optoelectronic technologies, so this structure can be used in the next generation of all-optical high-speed central processing units.

Keywords:

High-speed , all-optical , half-adder , photonic crystals , photonic bandgap