Route-asymmetrical optical transmission and logic gate based on optical gradient force.

We put forward a route-asymmetrical optical transmission scheme employing optical gradient force, which means that forward and backward propagation of an optical device have different transmittance provided they are not present simultaneously. The device is based on optical gradient force between two single-mode waveguides followed by a Mach-Zehnder interferometer. Our numerical investigation shows that the forward transmittance is about -6 dB while the backward transmittance is suppressed below -20.5 dB in C + L bands. The proposed device is passive, wideband, and compatible with complementary metal-oxide semiconductor (CMOS) process. Furthermore, we demonstrate the applications of route-asymmetrical transmission such as an all-optical switch and all-optical AND gate for all-optical information processing.