Nonreciprocal Isolation and Wavelength Conversion via a Spatiotemporally Engineered Cascaded Cavity

The principle of reciprocity underpins one of the fundamental effects in optics that signifies symmetric transmission with respect to the interchange of the source and observation points. Breaking reciprocity, however, enables additional functionalities and greatly enriches the applications of photonics in terms of nonreciprocal devices. Here, a realistic nanoscale cascaded-cavity system that envisages nonreciprocal optical isolation and efficient wavelength conversion based on spatiotemporally modulated index of refraction are proposed and numerically demonstrated. The on-chip, linear, magnetic-free nonreciprocal isolation and dynamically controllable wavelength conversion can be a promising candidate for silicon nanophotonic and optoelectronic devices.