Optical Isolation by Time-Dependent Sinusoidal-Shaped Structures

Design of nonmagnetic optical isolators integrated with silicon waveguides is important for rapidly growing silicon photonics in optical communications. We introduce a silicon waveguide consisting of an array of complex sinusoidal-shaped structures that create the designed time-dependent modulation of refractive indices. These time-dependent sinusoidal-shaped structures are engineered to have in-phase mode conversion only in one direction, thus leading to asymmetric optical mode conversion in the silicon waveguide and one-way light transmission with high contrast ratios, confirmed by numerically simulated field maps and calculated transmission at the wavelength of 1550 nm. Our design may offer another practical design to the compact chip-scale optical isolators in silicon waveguides.