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Nonreciprocal optical links based on time-modulated nanoantenna arrays: Full-duplex communication
摘要： Interference of transmitted and received signals hinders the simultaneous functionality of a conventional optical antenna as a transmitter and receiver which is required for full-duplex communication. The full-duplex communication schemes enabled by dense wavelength division multiplexed optical networks require distinct transmitter/receiver components operating at different wavelengths which increase the cost, complexity, and footprint of the physical layer. In this work, we demonstrate that an array of nanoantennas with leaky-wave architecture based on spatiotemporal modulation establishes nonreciprocal optical links which can reject the interference of transmitted and received signals by isolating the frequency of transmission and reception modes. For this purpose, we integrate indium-tin oxide into plasmonic nanodipoles which allows for realization of time-modulated nanoantennas in near-infrared frequency regime through electrical modulation of charge carrier density with radio-frequency signals. The radiation characteristics of individual nanoantennas and modal properties of nanoantenna arrays are rigorously studied through linking of charge transport and electromagnetic models. To this end, we extend the formulation of discrete dipole approximation as the standard modeling tool for electromagnetic scattering from nanoantenna arrays to treat realistic time-modulated structures with drastically different timescales between optical and modulation frequencies. The operation of spatiotemporally modulated array antennas in transmission and reception modes is investigated. Moreover, electrical beam-scanning functionality and dependence of antenna characteristics to modulation parameters and wavelength are demonstrated. It is rigorously established that such array antennas can operate as full transceivers by separating the transmitted and received signals propagating along the same direction through down conversion and up conversion of the frequency. Our results provide a route toward realization of optical antenna systems capable of full-duplex communication and real-time beam scanning which can increase the capacity and decrease the complexity of optical networks.
关键词： nonreciprocal optical links,indium-tin oxide,leaky-wave antenna,discrete dipole approximation,full-duplex communication,time-modulated nanoantenna arrays,spatiotemporal modulation
更新于2025-09-23 15:23:52
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[IEEE 2019 IEEE Research and Applications of Photonics in Defense Conference (RAPID) - Miramar Beach, FL, USA (2019.8.19-2019.8.21)] 2019 IEEE Research and Applications of Photonics in Defense Conference (RAPID) - Non-Reciprocal Graphene Gratings Based on Spatiotemporal Modulation
摘要： This paper presents a nonreciprocal grating based on graphene strips on top of a dielectric substrate for THz frequencies. Nonreciprocity is achieved by applying a directional temporal modulation with different phases to different graphene strips of the grating. Quite importantly, only three distinct modulation regions are necessary to achieve strong nonreciprocity, relaxing the fabrication requirements. Simulation results show very large isolation with moderate insertion loss for realistic parameters for graphene, making the proposed structure suitable for practical applications at THz frequencies.
关键词： spatiotemporal modulation,graphene,THz frequencies,nonreciprocal grating
更新于2025-09-12 10:27:22