Abstract-Tunable hybridization of graphene plasmons and dielectric modes for highly confined light transmit at terahertz wavelength

X. Q. He, T. G. Ning, L. Pei, J. J. Zheng, J. Li, and X. D. Wen

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-27-5-5961

We theoretically report a novel graphene-based hybrid plasmonic waveguide (GHPW) by integrating a GaAs micro-tube on a silica spacer that is supported by a graphene-coated substrate. In comprehensive numerical simulations on guiding properties of the GHPW, it was found that the size of hybrid plasmonic mode (TM) can be reduced significantly to ~10−4(λ2/4), in conjunction with long propagation distances up to tens of micrometers by tuning the the waveguide’s key structure parameters and graphene’s chemical potential. Moreover, crosstalk between two adjacent GHPWs that are placed on the same substrate has been analyzed and ultralow crosstalk can be realized. The proposed scheme potentially enables realization of the various high performance nanophotonic components-based subwavelength plasmonic waveguides in terahertz domain.

© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-27-5-5961

Abstract-Graphene Surface-polariton in-Plane Cherenkov Radiation

Jin Tao,  Lin Wu, Guoxing Zheng

https://www.blogger.com/blogger.g?blogID=124073320791841682#editor/target=post;postID=7421418378889081700

The Cherenkov plasmonic radiation in/parallel graphene plane is demonstrated theoretically. It is shown that the graphene Cherenkov radiation can be excited by a moving electron at a relative lower speed, which greatly reduced the difficulty for the Cherenkov radiation realization due to the low phase velocity and high field confinement of graphene plasmons. The excited graphene plasmons wavelength and the Cherenkov radiation angle can be dynamically changed by varying the Femi energy levels, which provides a versatile, tunable mechanism for plasmonic Cherenkov effect in active integrated photonic applications.

Abstract-Transition radiation from graphene plasmons by a bunch beam in the terahertz regime

Kai-Chun Zhang, Xiao-Xing Chen, Chang-Jian Sheng, Kelvin J. A. Ooi, Lay Kee Ang, and Xue-Song Yuan

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-17-20477

The terahertz band is an increasingly important spectrum in a wide range of applications from bioimaging and medical diagnostics to security and wireless communications. We propose a tunable terahertz coherent radiation source based on graphene plasmon-induced transition radiation. The transition radiation in terahertz regime arises from the graphene plasmons, which are excited by a normally incident bunched electron beam. We analyze the field-intensities and spectral-angular distributions of the transition radiation with respect to Fermi energy, substrate dielectric permittivity, and electron bunch energy for both the coherent and incoherent radiation. The effect of electron bunching on the radiation pattern is discussed. The mechanism of plasmon frequency-selective transition radiation is discovered.

© 2017 Optical Society of America

Abstract-Electrical 2π phase control of infrared light in a 350-nm footprint using graphene plasmons

• Achim Woessner,
• Yuanda Gao,
• Iacopo Torre,
• Mark B. Lundeberg,
• Cheng Tan,
• Kenji Watanabe,
• Takashi Taniguchi,
• Rainer Hillenbrand,
• James Hone,
• Marco Polini
• & Frank H. L. Koppens
• 
  

http://www.nature.com/nphoton/journal/vaop/ncurrent/full/nphoton.2017.98.html

Modulating the amplitude and phase of light is at the heart of many applications such as wavefront shaping, transformation optics, phased arrays, modulators and sensors. Performing this task with high efficiency and small footprint is a formidable challenge. Metasurfaces and plasmonics are promising, but metals exhibit weak electro-optic effects. Two-dimensional materials, such as graphene, have shown great performance as modulators with small drive voltages. Here, we show a graphene plasmonic phase modulator that is capable of tuning the phase between 0 and 2π in situ. The device length of 350 nm is more than 30 times shorter than the 10.6 μm free-space wavelength. The modulation is achieved by spatially controlling the plasmon phase velocity in a device where the spatial carrier density profile is tunable. We provide a scattering theory for plasmons propagating through spatial density profiles. This work constitutes a first step towards two-dimensional transformation optics for ultracompact modulators and biosensing.

Abstract-Gain modulation by graphene plasmons in aperiodic lattice lasers

1. S. Chakraborty1,*, 
2. O. P. Marshall1,2, 
3. T. G. Folland1, 
4. Y.-J. Kim2, 
5. A. N. Grigorenko2, 
6. K. S. Novoselov2,*

1. 1School of Electrical and Electronic Engineering, University of Manchester, Manchester M13 9PL, UK.
2. 2School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK.

1. ↵*Corresponding author. E-mail: s.chakraborty@manchester.ac.uk (S.C.); kostya@manchester.ac.uk (K.S.N.)

Science  15 Jan 2016:
Vol. 351, Issue 6270, pp. 246-248
DOI: 10.1126/science.aad2930

http://science.sciencemag.org/content/351/6270/246

Two-dimensional graphene plasmon-based technologies will enable the development of fast, compact, and inexpensive active photonic elements because, unlike plasmons in other materials, graphene plasmons can be tuned via the doping level. Such tuning is harnessed within terahertz quantum cascade lasers to reversibly alter their emission. This is achieved in two key steps: first, by exciting graphene plasmons within an aperiodic lattice laser and, second, by engineering photon lifetimes, linking graphene’s Fermi energy with the round-trip gain. Modal gain and hence laser spectra are highly sensitive to the doping of an integrated, electrically controllable, graphene layer. Demonstration of the integrated graphene plasmon laser principle lays the foundation for a new generation of active, programmable plasmonic metamaterials with major implications across photonics, material sciences, and nanotechnology.

Tuning terahertz lasers via graphene plasmons

1. Marco Polini

http://science.sciencemag.org/content/351/6270/229?rss=1

1. Graphene Labs, Istituto Italiano di Tecnologia, Via Morego 30, I-16163 Genova, Italy.

1. E-mail: marco.polini@iit.it

Science  15 Jan 2016:
Vol. 351, Issue 6270, pp. 229-231
DOI: 10.1126/science.aad7995

Plasmons (1) are collective density oscillations that pertain to charged particles, such as electrons and holes in solids. Although plasmons are often associated with metals, they are being actively explored for graphene and related two-dimensional materials (2DMs). Graphene plasmons (GPs) (2) can achieve active functionalities in diverse device types. For example, mid-infrared (mid-IR) GPs have been used to enhance mid-IR photodetectors (3), vibrational sensing of surface-adsorbed polymers (4), and label-free detection of protein monolayers (5). On page 246 of this issue, Chakraborty et al. (6) show that tunable graphene optical properties and GPs can be used to modulate the emission of a terahertz (THz) quantum cascade laser (7). Electromagnetic waves in the THz range (frequencies ν between 0.3 and 10 THz, or wavelengths γ between 50 µm and 1 mm) can penetrate many materials and have many applications in imaging and spectroscopy.