Forogh Pakrai - Department of Electrical Engineering, Mahshahr Branch, Islamic Azad University, Mahshahr, Iran.
Mohammad Soroosh - Department of Electrical Engineering, Shahid Chamran University of Ahvaz, Ahvaz,Iran.
jabbar ganji - Department of Electrical Engineering, Mahshahr Branch, Islamic Azad University,Mahshahr, Iran.

Abstract Using a photonic crystal array, an all-opticalhalf-subtractor has been designed that consists of fourresonant rings and some waveguides which connect twoinput ports to output ports. The silicon rods with a periodof ۰.۶۳۱ μm are arranged in the form of a square.Concerning the four working states of the device,different radii of nonlinear rods inside the resonatorshave been chosen. This issue makes the differentswitching thresholds for the rings and results in thecorrect dropping operation for optical waves. Unlike theprevious works, each bit is defined to one port, and theinput ports have equal power. The maximum rise timeand the contrast ratio of the presented circuit are ۳.۵ psand ۸.۴۵ dB, respectively. The fast response and smallsize are the main advantages of the presented subtractor.The obtained results demonstrates that the designeddevice has an acceptable performance which is proper foroptical applications.

Half-subtractor, Optical Kerr effect, Photonic Crystal, Resonant ring