ﻻ يوجد ملخص باللغة العربية
This tutorial provides an intuitive and concrete description of the phenomena of electromagnetic nonreciprocity that will be useful for readers with engineering or physics backgrounds. The notion of time reversal and its different definitions are discussed with special emphasis to its relationship with the reciprocity concept. Starting from the Onsager reciprocal relations generally applicable to many physical processes, we present the derivation of the Lorentz theorem and discuss other implications of reciprocity for electromagnetic systems. Next, we identify all possible routes towards engineering nonreciprocal devices and analyze in detail three of them: Based on external bias, based on nonlinear and time-variant systems. The principles of the operation of different nonreciprocal devices are explained. We address the similarity and fundamental difference between nonreciprocal effects and asymmetric transmission in reciprocal systems. In addition to the tutorial description of the topic, the manuscript also contains original findings. In particular, general classification of reciprocal and nonreciprocal phenomena in linear bianisotropic media based on the space- and time-reversal symmetries is presented. This classification serves as a powerful tool for drawing analogies between seemingly distinct effects having the same physical origin and can be used for predicting novel electromagnetic phenomena. Furthermore, electromagnetic reciprocity theorem for time-varying systems is derived and its applicability is discussed.
Emerging photonic functionalities are mostly governed by the fundamental principle of Lorentz reciprocity. Lifting the constraints imposed by this principle could circumvent deleterious effects that limit the performance of photonic systems. A variet
In recent years a significant progress has been made in the development of magnet-less nonreciprocity using space-time modulation, both in electromagnetics and acoustics. This approach has so far resulted in a plethora of non-reciprocal devices, such
We propose how to realize nonreciprocity for a weak input optical field via nonlinearity and synthetic magnetism. We show that the photons transmitting from a linear cavity to a nonlinear cavity (i.e., an asymmetric nonlinear optical molecule) exhibi
We introduce chiral gradient metasurfaces that allow perfect transmission of all the incident wave into a desired direction and simultaneous perfect rotation of the polarization of the refracted wave with respect to the incident one. Besides using gr
We propose the concept of helicity maximization applicable to structured light and obtain a universal rela-tion for the maximum of helicity density at a given field energy density. We further demonstrate that us-ing structured light with maximized he