Abstract-Modulation of terahertz radiation from graphene surface plasmon polaritons via surface acoustic wave

Sichen Jin, Xinke Wang, Peng Han, Wenfeng Sun, Shengfei Feng, Jiasheng Ye, Chao Zhang,  Yan Zhang,

Fig. 1 (a) Three-dimensional and (b) side schematic views of a moving electron beam atop a graphene layer on a piezoelectric MoS2 flake under an applied surface acoustic wave (SAW) field. The vacuum layer, the MoS2 flake with the applied SAW field, and the substrate layer are labeled as regions I, II, and III, respectively. The distance between the electron beam and the graphene layer and the thickness of the MoS2flake are labeled 𝑏$b$ and d$\text{d}$, respectively. (c) Schematic illustration of the electron and hole distributions in the SAW-induced type-II band-edge modulation of the n-doped MoS2 flake.

https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-27-8-11137

We present a theoretical study of terahertz (THz) radiation induced by surface plasmon polaritons (SPPs) on a graphene layer under modulation by a surface acoustic wave (SAW). In our gedanken experiment, SPPs are excited by an electron beam moving on a graphene layer situated on a piezoelectric MoS2 flake. Under modulation by the SAW field, charge carriers are periodically distributed over the MoS2 flake, and this causes periodically distributed permittivity. The periodic permittivity structure of the MoS2 flake folds the SPP dispersion curve back into the center of the first Brillouin zone, in a manner analogous to a crystal, leading to THz radiation emission with conservation of the wavevectors between the SPPs and the electromagnetic waves. Both the frequency and the intensity of the THz radiation are tuned by adjusting the chemical potential of the graphene layer, the MoS2 flake doping density, and the wavelength and period of the external SAW field. A maximum energy conversion efficiency as high as ninety percent was obtained from our model calculations. These results indicate an opportunity to develop highly tunable and integratable THz sources based on graphene device.https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-27-8-11137

Abstract-Broadband Electromagnetic Waves Harvesting Based on Effective Surface Plasmon Polaritons

Kuan Wang, Zhuo Li, Liangliang Liu, Yu Luo,

https://www.researchgate.net/publication/325830597_Broadband_Electromagnetic_Waves_Harvesting_Based_on_Effective_Surface_Plasmon_Polaritons

In this paper, a novel structure is proposed for broadband electromagnetic energy harvesting based on effective surface plasmon polaritons (ESPPs) under the framework of conformal transformation optics(TO). By inserting a dielectric cylindrical structure with crescent-shaped cross-section into a dielectric-filled rectangular waveguide, the transverse-electric (TE) mode in the waveguide is smoothly transformed into ESPPs at the bottom of the crescent and propagate towards the singularity of the crescent with decreasing velocity down to zero. The ESPPs energy is harvested all the way towards the singularity due to the interaction between compressed ESPPs and the surrounding lossy dielectrics and metallic wires. Simulation results show that broadband transformation and energy harvesting of ESPPs with efficiency about 25% can be achieved in this scheme. This work paves the way for broadband EM energy harvesting at microwave and terahertz frequencies.

Abstract- Rainbow Trapping in Highly Doped Silicon Graded Grating Strip at the Terahertz Range

Yan Liu,  Ruoying Kanyang, Genquan Han, Yao Shao, Cizhe Fang ;  Yan Huang,  Siqing Zhang,   Jincheng Zhang

https://ieeexplore.ieee.org/document/8318699/

In this paper, we propose surface plasma polaritons (SPPs) propagating along the structure of grating grooves based on highly doped silicon, which exhibits better performance of exciting SPPs than metal at low frequency (e.g., microwaves, mid infrared, and terahertz). The dispersive properties of the gradient-corrugated grating waveguides are characterized using the computer simulation technology microwave studio. Moreover, the propagation characteristics of the highly doped silicon grating structure are analyzed in detail by the dispersion curves, two-dimensional electric field magnitude distributions, the propagation loss, and the SPP lifetime. It is demonstrated that the gradient-corrugated grating waveguides based on heavily doped silicon could excite SPPs and realize rainbow trapping. The lifetime of the plasmonic mode can reach a value of 1200 ps, which may be long enough for some meaningful nanophotonic applications. The highly doped silicon is an ideal candidate for making practical use of the slow-light system in optical communication and various nanophotonic circuits, which permits further application for compact plasmonic devices.

Researchers squeeze light into nanoscale devices and circuits

https://www.nanowerk.com/nanotechnology-news/newsid=50272.php

(Nanowerk News) As electronic devices and circuits shrink into the nanoscale, the ability to transfer data on a chip, at low power with little energy loss, is becoming a critical challenge. Over the past decade, squeezing light into tiny devices and circuits has been a major goal of nanophotonics researchers.

Electronic oscillations at the surface of metals, known as surface plasmon polaritons or plasmons for short, have become an intense area of focus. Plasmons are hybrids of light (photons) and electrons in a metal. If researchers can harness this nanolight, they will be able to improve sensing, subwavelength waveguiding, and optical transmission of signals.

Columbia investigators have made a major breakthrough in this research, with their invention of a novel “home-built” cryogenic near-field optical microscope that has enabled them to directly image, for the first time, the propagation and dynamics of graphene plasmons at variable temperatures down to negative 250 degrees Celsius. The study was published online today in Nature ("Fundamental limits to graphene plasmonics").

The best pictorial representation of a surface plasmon polariton is in terms of a “ripple” of electron density on the surface of graphene sample. (Image: Dimitri Basov/Columbia University)

“Our temperature-dependent study now gives us direct physical insight into the fundamental physics of plasmon propagation in graphene,” says Dimitri N. Basov, professor of physics at Columbia University, who led the study together with colleagues Cory Dean (physics) and James Hone (mechanical engineering, Columbia Engineering). “This insight was impossible to attain in previous nanoimaging studies done at room temperature. We were particularly surprised at discovering, after many years of failed attempts to get anywhere close, that compact nanolight can travel along the surface of graphene for distances of many tens of microns without unwanted scattering. The physics limiting the travel range of nanolight is a fundamental finding of our study and may lead to new applications in sensors, imaging, and signal processing.”

Basov, Dean, and Hone bring together years of experience in working with graphene, the one-atom-thick material that is one of the most promising candidates for novel photonic materials. Graphene’s optical properties are readily tunable and can be altered at ultrafast time scales. However, implementing nanolight without introducing unwanted dissipation in graphene has been very difficult to achieve.

The Columbia researchers developed a practical approach to confining light to the nanoscale. They knew they could form plasmon-polaritons, or resonant modes, in the graphene that propagate through the material as hybrid excitations of light and mobile electrons. These plasmon-polariton modes can confine the energy of electromagnetic radiation, or light, down to the nanoscale. The challenge was how to visualize these waves with ultra-high spatial resolution, so that they could study the performance of plasmonic modes at varying temperatures.

Alexander S. McLeod, a postdoctoral research scientist in the Basov Nano-optics Laboratory, built a unique microscope that enabled the team to explore the plasmon-polariton waves at high resolution while they cooled the graphene to cryogenic temperatures. Lowering the temperatures allowed them to “turn off” various scattering, or dissipation, mechanisms, one after another, as they cooled down their samples and learned which mechanisms were relevant.

“Now that our novel nanoimaging capabilities are deployed to low temperatures, we can see directly the unmitigated wave propagation of collective light-and-charge excitations within graphene,” says McLeod, co-lead author of the study with Guangxin Ni, also a postdoctoral research scientist in Basov’s lab. “Often times in physics, as in life, seeing truly is believing! The record-breaking travel range of these waves shows they’re destined to take on a life of their own, funneling signals and information back and forth inside next-generation optical devices.”

The study is the first to demonstrate the fundamental limitations for the propagation of plasmon polariton waves in graphene. The team found that graphene plasmons propagate ballistically, across tens of micrometers, throughout the tiny device. These plasmon modes are confined within a volume of space hundreds, if not thousands, of times smaller than that occupied by freely propagating light.

Plasmons in graphene can be tuned and controlled via an external electric field, which gives graphene a big advantage over conventional plasmonic media such as metal surfaces, which are inherently non-tunable. Moreover, the lifetimes of plasmon waves in graphene are now found to exceed those in metals by a factor of 10 to a 100, while propagating over comparably longer distances. These features offer enormous advantages for graphene as a plasmonic medium in next-generation opto-electronic circuits.

“Our results establish that graphene ranks among the best candidate materials for infrared plasmonics, with applications in imaging, sensing, and nano-scale manipulation of light,” says Hone. “Furthermore, our findings reveal the fundamental physics of processes that limit propagation of plasmon waves in graphene. This monumental insight will guide future efforts in nanostructure engineering, which may be able to remove the remaining roadblocks for long-range travel of versatile nanoconfined light within future optical devices.”

The current study is the beginning of a series of low-temperature investigations focused on controlling and manipulating confined plasmons in nanoscale optoelectronic graphene devices. The team is now using low-temperature nanoimaging to explore novel plasmonics effects such as electrically-induced plasmonic reflection and modulation, topological chiral plasmons, and also superconducting plasmonics in the very recently discovered “magic angle” system of twisted bilayer graphene.

Source: By Holly Evarts, Columbia University

Abstract-Light controlled surface plasmon polaritons switch based on a gradient metal grating

Lidan Cao, 

Yan Zhang

https://www.sciencedirect.com/science/article/pii/S0030401818303365

A surface plasmon polaritons (SPPs) switch controlled by a pump light in the terahertz (THz) regime is designed. The switch is based on the surface slow-light technology. A gradient metal grating on a silicon (Si) layer is adopted to slow the SPP waves. By adjusting the grade of grating depths, the location of stopped waves can be tuned. By changing the intensity of pump light shining on the Si layer, the carrier density of Si layer can be modulated and thus the dielectric constant of Si layer. Then the SPPs can switched between two states: going through the structure or being stopped. The bandwidth of the captured surface wave can be effectively broaden by using this kind of depth gradient grating. This approach may provide a new method to design controllable SPPs devices.

Abstract- Novel Surface Plasmon Polariton Waveguides with Enhanced Field Confinement for Microwave-Frequency Ultra-Wideband Bandpass Filters

Ying Jiang Guo,  Kai Da Xu,  Yanhui Liu,  Xiaohong Tang,

Schematic view of the ultra-wideband BPF using proposed SSPP waveguide.

https://ieeexplore.ieee.org/document/8301436/

In this paper, a novel planar waveguide based on spoof surface plasmon polaritons (SSPPs) using fish-bone corrugated slot structure is first proposed in the microwave region. Low-dispersion band can be realized by such structure with tight field confinement of SSPPs, resulting in size miniaturization of the proposed waveguide. The high frequency stopband of the proposed ultra-wideband bandpass filter (BPF) is created by using this proposed waveguide, while the low frequency stopband is properly designed through introducing the microstrip-to-slotline transition. The 2-D E-fields distribution, surface current flow, and energy flow patterns are all calculated and illustrated to demonstrate the electromagnetic (EM) characteristics of the proposed ultra-wideband BPF. The BPF tuning characteristics is explored to provide a guideline for facilitating the design process. To validate the predicted performance, the proposed filter is finally designed, fabricated, and measured. Measured results illustrate high performance of the filter, in which the reflection coefficient is better than -10 dB from 2.1 to 8 GHz with the smallest insertion loss of 0.37 dB at 4.9 GHz, showing good agreement with numerical simulations. The proposed surface plasmon polariton waveguides are believed to be significantly promising for further developing plasmonic functional devices and integrated 2-D circuits with enhanced confinement of SSPPs in microwave and even terahertz bands.

Abstract-Surface plasmon-mediated nanoscale localization of laser-driven sub-THz spin dynamics in magnetic dielectrics

Alexander Chekhov, Alexander I. Stognij, T. Satoh, Tatiana V. Murzina, I. Razdolski, Andrzej Stupakiewicz,

https://pubs.acs.org/doi/abs/10.1021/acs.nanolett.8b00416?journalCode=nalefd

We report spatial localization of the effective magnetic field generated via the inverse Faraday effect employing surface plasmon polaritons (SPPs) at a hybrid Au/rare-earth iron garnet interface. Analyzing, both numerically and analytically, the electric field of the SPPs at a hybrid interface, we corroborate our study with a proof-of-concept experiment showing efficient SPP-driven excitation of coherent spin precession with a 0.41 THz frequency. We argue that the sub-diffractional confinement of the SPP electric field enables strong spatial localization of the SPP-mediated excitation of spin dynamics. We demonstrate a two orders of magnitude enhancement of the excitation efficiency at the surface plasmon resonance within a 100 nm layer of a dielectric garnet. Our findings broaden the horizons of ultrafast spin-plasmonics and open pathways towards non-thermal opto-magnetic recording on the nanoscale.

Abstract-Terahertz imaging sensor based on the strong coupling of surface plasmon polaritons between PVDF and graphene

Jiaqi Zhu, Banxian Ruan, Qi You, Jun Guo,  Xiaoyu Dai, Yuanjiang Xiang

https://www.sciencedirect.com/science/article/pii/S0925400518304696
Surface plasmon polaritons (SPPs) of metal materials such as gold and silver are excited in the visible and near-infrared band, while the graphene SPPs exist from mid-infrared to terahertz (THz) ranges. Hence it is difficult to realize the coupling of SPPs of metals and graphene. In this paper, we realize coupling of two SPPs modes based on graphene and polyvinylidene fluoride (PVDF) in THz range, which is vital for the research of new sensors in terahertz spectrum. Based on the dispersion relation, it is demonstrated that the two different THz SPP modes in the hybrid configuration can be coupled together. We apply our design to the imaging sensor, and the highest imaging sensitivity as high as 730RIU⁻¹ is realized in the proposed sensors (which can be used in gas detection). Our results suggest that the strong coupling of two SPPs modes is an efficient method to achieve high sensing properties for the devices.

Abstract-Tuning the dispersion of effective surface plasmon polaritons with multilayer systems

Zhuo Li, Yunhe Sun, Kuan Wang, Jiajia Song, Jianfeng Shi, Changqing Gu, Liangliang Liu, and Yu Luo

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-4-4686&origin=search

Recently, effective surface plasmon polaritons (ESPPs) induced by structural dispersion in bounded waveguides were theoretically demonstrated and experimentally verified. Despite the theoretical and experimental efforts, whether ESPPs can mimic real SPPs in every aspect still remains an open question. In this work, we go one step further to study the hybridization of ESPPs in multilayer systems. We consider transverse electric (TE) modes in a conventional rectangular waveguide and a parallel-plate waveguide (PPW) and derive analytically the dispersion relations and asymptotic frequencies of the corresponding ESPPs modes in sandwiched structures consisting of alternating dielectrics of different permittivities. Our results show that the ESPPs can be categorized into odd and even parities (owing to the ‘plasmon’ hybridization) in a similar way as natural SPPs supported by the insulator/metal/insulator (IMI) and metal/insulator/metal (MIM) heterostructures in the optical regime. The similarities and differences between ESSPs and their optical counterparts are also discussed in details, which may provide valuable guidance for future application of ESPPs at the microwave and terahertz frequencies.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Observation of graphene surface plasmon polaritons excited by free electron beam

Min Hu,  Sen Gong, Tao Zhao,  Renbin Zhong,  Chengpeng Yu,   Shenggang Liu

http://ieeexplore.ieee.org/document/8066948/

In previous work, we propose to develop a novel kind of terahertz radiation source which utilizing free electron beam to excited graphene surface plasmon polaritons (GSPPs) combining vacuum electronics and new 2D material graphene. The previous theoretical analysis show that this coherent radiation source can be tuned covering almost whole THz frequency range and work at room temperature. In this paper, we demonstrate the conductivity mapping of GSPPs with free electron beam excitation using TDS system. The characteristics of GSPPs can be derived from the calculated conductivity results and be compared with the theoretical Drude model, which would guide the next step of the experiment to realize the new kind of THz source.

Abstract-Terahertz spoof surface-plasmon-polariton subwavelength waveguide

Ying Zhang, Yuehong Xu, Chunxiu Tian, Quan Xu, Xueqian Zhang, Yanfeng Li, Xixiang Zhang, Jiaguang Han, and Weili Zhang

https://www.osapublishing.org/prj/abstract.cfm?uri=prj-6-1-18&origin=search

Surface plasmon polaritons (SPPs) with the features of subwavelength confinement and strong enhancements have sparked enormous interest. However, in the terahertz regime, due to the perfect conductivities of most metals, it is hard to realize the strong confinement of SPPs, even though the propagation loss could be sufficiently low. One main approach to circumvent this problem is to exploit spoof SPPs, which are expected to exhibit useful subwavelength confinement and relative low propagation loss at terahertz frequencies. Here we report the design, fabrication, and characterization of terahertz spoof SPP waveguides based on corrugated metal surfaces. The various waveguide components, including a straight waveguide, an S-bend waveguide, a Y-splitter, and a directional coupler, were experimentally demonstrated using scanning near-field terahertz microscopy. The proposed waveguide indeed enables propagation, bending, splitting, and coupling of terahertz SPPs and thus paves a new way for the development of flexible and compact plasmonic circuits operating at terahertz frequencies.

© 2017 Chinese Laser Press

Abstract-Plasmonics of magnetic and topological graphene-based nanostructures

Dmitry A. Kuzmin, Igor V. Bychkov, Vladimir G. Shavrov, Vasily V. Temnov

https://arxiv.org/abs/1711.10777

Graphene is a unique material to study fundamental limits of plasmonics. Apart from the ultimate single-layer thickness, its carrier concentration can be tuned by chemical doping or applying an electric field. In this manner the electrodynamic properties of graphene can be varied from highly conductive to dielectric. Graphene supports strongly confined, propagating surface plasmon-polaritons (SPPs) in a broad spectral range from terahertz to mid-infrared frequencies. It also possesses a strong magneto-optical response and thus provides complimentary architectures to conventional magneto-plasmonics based on magneto-optically active metals or dielectrics. Despite of a large number of review articles devoted to plasmonic properties and applications of graphene, little is known about graphene magneto-plasmonics and topological effects in graphene-based nanostructures, which represent the main subject of this review. We discuss several strategies to enhance plasmonic effects in topologically distinct closed surface landscapes, i.e. graphene nanotubes, cylindric nanocavities and toroidal nanostructures. A novel phenomenon of the strongly asymmetric SPP propagation on chiral meta-structures and fundamental relations between structural and plasmonic topological indices are reviewed.

Abstract-Spontaneous emission in plasmonic graphene subwavelength wires of arbitrary sections

Mauro Cuevas

https://www.sciencedirect.com/science/article/pii/S0022407317305964

We present a theoretical study of the spontaneous emission of a line dipole source embedded in a graphene–coated subwavelength wire of arbitrary shape. The modification of the emission and the radiation efficiencies are calculated by means of a rigorous electromagnetic method based on Green’s second identity. Enhancement of these efficiencies is observed when the emission frequency coincides with one of the plasmonic resonance frequencies of the wire. The relevance of the dipole emitter position and the dipole moment orientation are evaluated. We present calculations of the near–field distribution for different frequencies which reveal the multipolar order of the plasmonic resonances.

Abstract-Tunable wavelength demultiplexer using modified graphene plasmonic split ring resonators for terahertz communication

Neetu Joshi, Nagendra P .Pathak,

http://www.sciencedirect.com/science/article/pii/S1569441017302420

This paper presents graphene modified ring resonator based wavelength demultiplexer (WDM) for THz device applications that is, a surface plasmon polaritons (SPPs) demultiplexer consisting of two nanostrip waveguides at input as well as output coupled to each other by a split ring resonator (SRR), which is modified in shape as compared to a simple ring-shaped resonator. A systematic analysis of the transmission spectra for the graphene based SRR poses clear insight on the demultiplexing phenomenon of the proposed nanodevice. The results show resonance peaks in the transmission spectrum, having a linear relationship with the chemical potential of graphene. The influence of structural parameters have also been analyzed. The tuning capability of graphene based tunable WDM, lays its foundation in the applications of optical switches, modulators, etc.

Abstract-Tunable unidirectional surface plasmon polariton launcher utilizing a graphene-based single asymmetric nanoantenna

Lei Huang, Shan Wu, Yulin Wang, Xiangjun Ma, Hongmei Deng, Shuming Wang, Ye Lu, Chuanqi Li, and Tao Li

https://www.osapublishing.org/ome/abstract.cfm?uri=ome-7-2-569&origin=search

We design and numerically investigate a graphene-based asymmetric nanoantenna microstructure that can be used to realize electrically controllable, unidirectionally propagating broadband surface plasmon polaritons. The device geometry facilitates the simultaneous excitation of two localized surface plasmons resonances in the whole structure, and consequently, the asymmetric nanoantenna can be considered as being composed of two oscillating magnetic dipoles, wherein the interference of the radiated electromagnetic waves leads to a unidirectional propagation effect. Our results indicate that our proposed active device is promising for realizing compactable, tunable, terahertz plasmonic light sources.

© 2017 Optical Society of America

Abstract-Adiabatic control of surface plasmon-polaritons in a 3-layers graphene curved configuration

Wei Huang,  Shi-Jun Liang,  L.K. Ang,

http://www.sciencedirect.com/science/article/pii/S0008622317310886

In this paper, we utilize coupled mode theory (CMT) to model the coupling between surface plasmon-polaritons (SPPs) between multiple graphene sheets. By using the Stimulated Raman Adiabatic Passage (STIRAP) Quantum Control Technique, we propose a novel directional coupler based on SPPs evolution in three layers of graphene sheets in some curved configuration. Our calculated results show that the SPPs can be transferred efficiently from the input graphene sheet to the output graphene sheet, and the coupling is also robust that it is not sensitive to the length of the device configuration's parameters and excited SPPs wavelength.

Abstract-Surface Plasmon Polariton Amplification in a Single Carbon Nanotube by Direct Electric Current

Sergey G. Moiseev, Aleksei S. Kadochkin, Yuliya S. Dadoenkova, and Igor O. Zolotovskii

https://www.osapublishing.org/abstract.cfm?uri=fio-2017-JW3A.45&origin=search

A mechanism of amplification of surface plasmon polaritons due to the transfer of electromagnetic energy from a drift current into a terahertz surface wave propagating along the single-walled carbon nanotube is proposed.

© 2017 OSA

Abstract-On-grating graphene surface plasmons enabling spatial differentiation in the terahertz region

Yisheng Fang, Yijie Lou, and Zhichao Ruan

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-42-19-3840

We propose a graphene-on-grating nanostructure to enable second-order spatial differentiation computation in the terahertz (THz) region. The differentiation operation is based on the interference between the direct reflected field and the leakage of two excited surface plasmon polaritons counter-propagating along the graphene sheet. With the spatial coupled-mode theory, we derive that the requirement for the second-order spatial differentiation is the critical coupling condition. We numerically demonstrate such an analog computation with Gaussian beams. It shows that the spatial bandwidth of the proposed differentiator is large enough such that even when the waist radius of the Gaussian beam is as narrow as 𝑤0=0.68𝜆$w_0=0.68\lambda$(𝜆$\lambda$ is the free-space wavelength), the accuracy of the differentiator is higher than 95%. The proposed differentiator is ultra-compact, with a thickness less than 0.1𝜆$0.1\lambda$, and useful for real-time imaging applications in THz security detections.

© 2017 Optical Society of America

Abstract-Terahertz surface plasmon polariton waveguiding with periodic metallic cylinders

Ying Zhang, Shaoxian Li, Quan Xu, Chunxiu Tian, Jianqiang Gu, Yanfeng Li, Zhen Tian, Chunmei Ouyang, Jiaguang Han, and Weili Zhang

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-13-14397

We demonstrated a structure with periodic cylinders arranged bilaterally and a thin dielectric layer covered inside that supports bound modes of surface plasmon polaritons at terahertz frequencies. This structure can confine the surface plasmon polaritons in the lateral direction, and at the same time reduce the field expansion into space. We examined and explored the characteristics of several different structures using scanning near-field terahertz microscopy. The proposed designs pave a novel way to terahertz waveguiding and may have important applications in the development of flexible, wideband and compact photonic circuits operating at terahertz frequencies.

© 2017 Optical Society of America

Abstract-Asymmetric optical transmission based on unidirectional excitation of surface plasmon polaritons in gradient metasurface

Yonghong Ling, Lirong Huang, Wei Hong, Tongjun Liu, Yali Sun, Jing Luan, and Gang Yuan

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-12-13648

Asymmetric optical transmission is fundamental and highly desirable in information processing and full manipulation of lightwave. We here propose an asymmetric optical transmission device consisting of a gradient metasurface and a one-dimensional subwavelength grating. Owing to the unidirectional excitation of surface plasmon polaritons (SPPs) by the gradient metasurface, and SPP-assisted extraordinary optical transmission, forward incident light has much higher transmission than the backward one. We combine temporal coupled mode theory and finite-difference time-domain simulations to verify its operation principle and study the performance. The results indicate that asymmetric transmission with high-contrast and large forward transmittance can be obtained around the 1.3 µm optical communication band.

© 2017 Optical Society of America