Sharif Digital Repository

In this paper we achieve non-reciprocity in a silicon optical ring resonator, by introducing two small time-modulated perturbations into the ring. Isolators are designed using this time-perturbed ring, side-coupled to waveguides. The underlying operation of the time-modulated ring and isolator is analyzed using Temporal Coupled Mode Theory (TCMT). The TCMT is used to find the angular distance, phase difference and thickness of the two time-modulated points on the ring resonator and also to find and justify the optimum values for the modulation frequency and amplitude, which yields maximum isolation in the isolator arrangements. Insight into the major players that determine isolation are also... 

In this Letter, we realize the concept of analog computing using an engineered gradient dielectric meta-reflect-array. The proposed configuration consists of individual subwavelength silicon nanobricks, in combination with a fused silica spacer and silver ground plane, realizing a reflection beam with full phase coverage of 2π degrees, as well as an amplitude range of 0 to 1. Spectrally overlapping electric and magnetic dipole resonances, such high-index dielectric metasurfaces can locally and independently manipulate the amplitude and phase of the incident electromagnetic wave. This practically feasible structure overcomes substantial limitations imposed by plasmonic metasurfaces such as...