Document Type
Article
Publication Date
1-27-2021
Abstract
Reciprocity is a fundamental physical principle that roots in the time-reversal symmetry of physical laws. It allows making predictions on any arbitrary complex system's response and operation and hence simplifies the analysis. However, there are many practical situations in which it is advantageous to break reciprocity, e.g., isolators preventing wave scattering back to lasers and generators, full-duplex systems for multiplexing transmission and receiving in the same channel, nonreciprocal cavity excitation, and protection of fragile states of superconductor quantum computers from thermal noise. The most widespread approach to time-reversal symmetry breaking and nonreciprocity based on magnetic field biasing suffers from bulkiness, cost ineffectiveness, and loss, motivating researchers and engineers to search for more practical approaches. Herein, the up-and-coming advances in optical nonreciprocity, including new materials (Weyl semimetals, topological insulators, metasurfaces), active structures, time-modulation, parity-time (PT)-symmetry breaking, nonlinearity combined with a structural asymmetry, quantum nonlinearity, unidirectional gain and loss, chiral quantum states and valley polarization are overviewed. A general description of nonreciprocal systems is provided and the pros and cons of the mentioned approaches to nonreciprocity are discussed.
Included in
Electromagnetics and Photonics Commons, Electronic Devices and Semiconductor Manufacturing Commons, Quantum Physics Commons
Comments
This article was originally published in Advanced Photonics Research, available at https://doi.org/10.1002/adpr.202000104
This work is distributed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).