Multilayer photonic logic gate integrated into microelectronic chip

An all-optical XOR gate was designed to take advantage of the previously unused silicon dioxide (SiO2) interconnect layers in a microelectronic chip. The device relies on the coupling of modes between parallel waveguides and the interaction of the modes with the metal interconnects of a silicon chip to obtain a phase difference between input arms. When the signals from the two input arms interfere, the result is a logic XOR operation due to the phase difference. The design was numerically implemented, and a contrast of 18.7 dB was obtained with a 13.2-mu m-long logic gate. (C) 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.JNP.6.061607]