Skip to main content
dd
CIC nanoGUNE
  • en
  • es
  • eu

User account menu

  • Log in

Main Menu ES

  • nanoGUNE
    • At a Glance
    • Organization & Funding
    • People
    • Join us
    • Life
    • Newsroom
    • nanoPeople
  • Research
    • Research
    • Publications
    • Projects
    • External services
  • TechTransfer
    • TechTransfer
    • Start-ups
    • IP Portfolio
    • Industry collaborative research positions
    • Strategic lines
    • External services
    • News & events
  • Training
    • Master projects
    • Bachelor Final Projects
    • Summer Internships
    • Education University PHD
  • Society

User menu

  • Log in
  1. Home
  2. On-chip observation of THz graphene plasmons

On-chip observation of THz graphene plasmons

04/11/2016

Researchers developed a technique for imaging THz photocurrents with nanoscale resolution, and applied it to visualize strongly compressed THz waves (plasmons) in a graphene photodetector. The extremely short wavelengths and highly concentrated fields of these plasmons open new venues for the development of miniaturized optoelectronic THz devices (Nature Nanotechnology DOI: 10.1038/NNANO.2016.185)

Radiation in the terahertz (THz) frequency range is attracting large interest because of its manifold application potential for non-destructive imaging, next-generation wireless communication or sensing. But still, the generating, detecting and controlling of THz radiation faces numerous technological challenges. Particularly, the relatively long wavelengths (from 30 to 300 μm) of THz radiation require solutions for nanoscale integration of THz devices or for nanoscale sensing and imaging applications.

In recent years, graphene plasmonics has become a highly promising platform for shrinking THz waves. It is based on the interaction of light with collective electron oscillations in graphene, giving rise to electromagnetic waves that are called plasmons. The graphene plasmons propagate with strongly reduced wavelength and can concentrate THz fields to subwavelength-scale dimensions, while the plasmons themselves can be controlled electrically.

THz plasmons of extremely short wavelength propagate along the graphene sheet of a THz detector, as visualized with photocurrent images obtained by scanning probe microscopy.

Now, researchers at CIC nanoGUNE (San Sebastian, Spain) in collaboration with ICFO (Barcelona, Spain), IIT (Genova, Italy) - members of the EU Graphene Flagship - Columbia University (New York, USA), Radboud University (Nijmegen, Netherlands), NIM (Tsukuba, Japan) and Neaspec (Martinsried, Germany) could visualize strongly compressed and confined THz plasmons in a room-temperature THz detector based on graphene. To see the plasmons, they recorded a nanoscale map of the photocurrent that the detector produced while a sharp metal tip was scanned across it. The tip had the function to focus the THz illumination to a spot size of about 50 nm, which is about 2000 times smaller than the illumination wavelength. This new imaging technique, named THz photocurrent nanoscopy, provides unprecedented possibilities for characterizing optoelectronic properties at THz frequencies.

The team recorded photocurrent images of the graphene detector, while it was illuminated with THz radiation of around 100 μm wavelength. The images showed photocurrent oscillations revealing that THz plasmons with a more than 50 times reduced wavelength were propagating in the device while producing a photocurrent.

“In the beginning we were quite surprised about the extremely short plasmon wavelength, as THz graphene plasmons are typically much less compressed”, says former nanoGUNE researcher Pablo Alonso, now at the University of Oviedo, and first author of the work. “We managed to solve the puzzle by theoretical studies, which showed that the plasmons couple with the metal gate below the graphene”, he continues. “This coupling leads to an additional compression of the plasmons and an extreme field confinement, which could open the door towards various detector and sensor applications”, adds Rainer Hillenbrand, Ikerbasque Research Professor and Nanooptics Group Leader at nanoGUNE who led the research. The plasmons also show a linear dispersion – that means that their energy is proportional to their momentum - which could be beneficial for information and communication technologies. The team also analysed the lifetime of the THz plasmons, which showed that the damping of THz plasmons is determined by the impurities in the graphene.

THz photocurrent nanoscopy relies on the strong photothermoelectric effect in graphene, which transforms heat generated by THz fields, including that of THz plasmons, into a current. In the future, the strong thermoelectric effect could be also applied for on-chip THz plasmon detection in graphene plasmonic circuits. The technique for THz photocurrent nanoimaging could find further application potential beyond plasmon imaging, for example, for studying the local THz optoelectronic properties of other 2D materials, classical 2D electron gases or semiconductor nanostructures.

For further information:

Pablo Alonso-González, Alexey Y. Nikitin, Yuanda Gao, Achim Woessner, Mark B. Lundeberg, Alessandro Principi, Nicolò Forcellini, Wenjing Yan, Saül Vélez, Andreas. J. Huber, Kenji Watanabe, Takashi Taniguchi, Félix Casanova, Luis E. Hueso, Marco Polini, James Hone, Frank H. L. Koppens & Rainer Hillenbrand.

Nature Nanotechnology (2016) doi:10.1038/nnano.2016.185

Acoustic terahertz graphene plasmons revealed by photocurrent nanoscopy

 

Tags
Graphene
Plasmonics
Plasmonics
  • whatsapp
  • facebook
  • twitter
  • linkedin
  • print

Related news

  • 06/05/2025

    NanoGUNE starts building the Quantum Tower

  • 01/04/2025

    Donostia, the spintronics and orbitronics capital

  • 31/03/2025

    Mariana Medina, interviewed on Radio Euskadi about “How to create microbots to help conceive a baby”

  • 14/02/2025

    Review Article Highlights 25 Years of Modern Near-field Optical Nanoimaging

  • 11/02/2025

    Scientists synthesize 2D polyaniline crystal with unique metallic out-of-plane conductivity

  • CIC nanoGUNE
  • Tolosa Hiribidea, 76
  • E-20018 Donostia / San Sebastian
  • +34 943 574 000 · nano@nanogune.eu
  • Facebook Twitter Youtube Linkedin Instagram Subscribe to our Newsletter

Menú pie principal

  • nanoGUNE
  • Research
  • TechTransfer
  • Training
  • Society
  • nanoPeople

Menú pie servicios

  • External services
  • Publications
  • Seminars
  • Join us
  • Newsroom
  • Contractor profile
  • Corporate Compliance

Menú pie grupos

  • Nanomagnetism
  • Nanooptics
  • Self Assembly
  • Nanobiosystems
  • Nanodevices
  • Electron Microscopy

Menú pie grupos 2

  • Theory
  • Nanomaterials
  • Quantum-Probe Microscopy
  • Nanoengineering
  • Quantum Hardware

Funded by

  • EJ/GV
  • Diputación
  • FEDER
  • FEDER
  • Ministerio de Ciencia e Innovación

Member of

  • BRTA
  • SOMM

Distinctions

  • Distinción de Excelencia María de Maeztu 2022-2025
  • Excellence Research
  • UNE-166002

Menú legales

  • Accesibility
  • Legal notice
  • Privacy policy
  • Cookies policy
  • Confidentiality policy
by ACC