Calculus is a fundamental subject in mathematics and extensively used in physics and astronomy. Performing calculus operations by analog computing has received much recent research interest because of its high speed and large data throughput; however, current analog calculus frameworks suffer from bulky sizes and relatively low integration densities. In this work, we introduce the concept of an epsilon-near-zero (ENZ) metamaterial processing unit (MPU) that performs differentiation and integration on analog signals to achieve extreme miniaturization at the subwavelength scale by generating desired dispersions of the ENZ metamaterials with photonic doping. To show the feasibility of this proposal, we further build an experimental analog image edge extraction system with a differentiating ENZ-MPU as its compute core. With a computing density theoretically analyzed to be several tera-operations per second and square micrometer, the proposed ENZ-MPU is scalable and configurable for more complex computations, providing an effective solution for analog calculus operators with extreme computing density and data throughput.
Plasmonic phenomena on the surface between metal and dielectric have received extensive attention, and have boosted a series of exciting techniques. Plasmonics describes the interaction between light and electronics and shows great potential in nanophotonics, optoelectronic devices, quantum physics, and surface-enhanced spectroscopy, etc. However, plasmonic phenomena are always suffering from the inherent loss issue of plasmonic materials at optical frequency, which has restricted further applications of plasmonics. In this review, we focus on the technique of waveguide effective plasmonics, which is a feasible low-loss realization of plasmonic metamaterials in lower frequency based on the structural dispersion. This review provides the underlying physics of the waveguide effective plasmonics and its applications varying from classical plasmonic concepts to novel effective plasmonic devices. Finally, we make a brief discussion on the direction of future researches and a prospect of the potential applications.
Surface plasmon polaritons (SPPs) have attracted intensive attention for the unprecedented developments of light–matter interactions in optics and photonics, providing a feasible method for light confinement and transmission at a subwavelength scale. However, SPPs traditionally suffer from large losses due to the intrinsic dissipations and absorptions, which hinder further development and applications of SPPs. Here, we theoretically and experimentally investigate the concept of stepped waveguide metamaterials behaving as low-loss effective replicas of SPPs. The proposed structure without natural plasmonic material maintains the identical field configuration to that in regular SPP but avoids the inherent losses, outperforming regular low-loss SPP design with natural plasmonic materials on SPP propagation lengths. Furthermore, stepped waveguide metamaterial exhibits excellent compatibility in direct interconnections with arbitrary regular SPP and potentially represents a feasible route toward new SPP devices with low-loss advantages.
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