Design and Analysis of a Graphene Based Slotted Bowtie Optical Plasmonic Nanoantenna

A graphene-based modified bowtie plasmonic nanoantenna resonating in the optical frequency spectrum with the periodic directors created by the slots on top of the radiating structure has been proposed in this paper. In the field of nanophotonics, a few optical nanoantennas have been reported to construct multipath wireless nanolinks. At the telecommunication wavelength of 1550 nm (193.5 THz), the maximum directivity of 9.67 dBi has been reached due to the maximum absorption power of graphene sheet by selecting the chemical potential of 0.5 eV. Since graphene supports surface plasmon polariton waves and acts either as an absorptive or transparent medium for distinct chemical potentials, the proposed graphene-based slotted bowtie optical nanoantenna has been optimized to obtain a dynamically controlled triple-directional radiation beam. With this distinctive nature, a multipath intra or inter on-chip wireless nanolink for secure optical data transfer can be realized by integrating a set of our proposed optical plasmonic nanoantennas.

Raman analysis of the crystallinity degree for the local regions in Ge2Sb2Te5 films after laser exposure at different parameters

The evaluation of the crystallinity degree for the local regions in Ge2Sb2Te5 (GST) thin films after phase state transformation by laser pulses at 405 nm wavelength was analyzed using the Raman spectroscopy. The modes of laser radiation for controlling the reflectivity and transmissivity at 1550 nm telecommunication wavelength of the local regions in the GST film were established. The results obtained make it possible to implement the method of the completely optical control of the multilevel modulation of the optical signals for the integrated optics devices.

An Ultra-Compact Design of Plasmonic Memristor with Low Loss and High Extinction Efficiency Based on Enhanced Interaction between Filament and Concentrated Plasmon

We present a numerical design of the plasmonic memristive switching device operated at the telecommunication wavelength of 1.55 μm, which consists of a triangle-shaped metal taper mounted on top of a Si waveguide, with rational doping in the area below the apex of the taper. This device can achieve optimal vertical coupling of light energy from the Si waveguide to the plasmonic region and, at the same time, focus the plasmon into the apex of the metal taper. Moreover, the area with concentrated plasmon is overlapped with that where the memristive switching occurs, due to the formation/removal of the metallic nano-filament. As a result, the highly distinct transmission induced by the switching of the plasmonic memristor can be produced because of the maximized interactions between the filament and the plasmon. Our numerical simulation shows that the device hasa compact size (610 nm), low insertion loss (~1 dB), and high extinction efficiency (4.6 dB/μm). Additionally, we point out that stabilizing the size of the filament is critical to improve the operation repeatability of the plasmonic memristive switching device.

Integrated photonic metasystem for image classifications at telecommunication wavelength

Miniaturized image classifiers are potential for revolutionizing their applications in optical communication, autonomous vehicles, and healthcare. With deep diffractive neuron networks trained subwavelength structures, we demonstrate image recognitions by a passive silicon photonic metasystem. The metasystem implements high-throughput vector-by-matrix multiplications, enabled by 103 passive subwavelength phase shifters as weight elements in 1 mm2 footprint. The large weight matrix size incorporates the fabrication variation related uncertainties, and thus the pre-trained metasystem can perform machine learning tasks without post-tuning. A 15-pixel spatial pattern classifier reaches near 90% accuracy with femtosecond inputs. The metasystem’s superior parallelism (1015 bit/s) dramatically expand data processing capability of photonic integrated circuits, towards next generation low latency and low power photonic accelerators compatible with complementary metal-oxide-semiconductor manufacturing.

Numerical & Analytical Modeling of Plasmonic Filter with High Q-Factor Based on "Nanostructured Resonator"

In this paper, to achieve high quality filters, nanostructured plasmon resonators are proposed. The structure of proposed resonator is based on metal-dielectric-metal configuration and is designed in the range of 1550 nm telecommunication wavelength. To evaluate the proposed structure, finite difference time domain method as well as analytical method of coupled mode theory have been used. To obtain optimal results, the effects of the number of waveguides as well as the radius of circular and ring waveguides were investigated. The appropriate results will be obtained by considering a strong coupling between the incoming light and the surface plasmon. In addition, two transient and static wave structures have been used to evaluate the structure. The simulation results show that besides filtering behavior of the structure, it is possible to control the surface plasmon propagation speed in the proposed structure. Therefore, it is expected that the proposed structure will be used in many parts of a telecommunications link, including multiplexers, and multiplexers.