Sub-wavelength mid-infrared imaging of locally driven photocurrents using diamond campanile probes
Abstract Precise and high efficiency concentration of mid-infrared (mid-IR) light into sub-wavelength volumes is essential for probing low-energy excitations and achieving strong field enhancements, which is hindered by absorption losses and coupling inefficiencies at long wavelengths. Here, we introduce a diamond-based metal-insulator-metal campanile probe that adiabatically compresses free-space mid-infrared light (10 μm) into ≈ 0.7 μm domain. Integrated into a scanning photovoltage microscope, the probe enables sub-wavelength mapping of locally driven photocurrents in graphene, resolving polarization-dependent and contact-sensitive responses at energies down to ≈ 0.1 eV. Experiments reveal a photocurrent signal density enhancement of 10 3 , coupling light power efficiencies above 1%, and an 18-fold increase in near-field light flux density, in agreement with numerical simulations. Operation of the probe with quantum cascade and free-electron lasers demonstrates a robust, spectrally tunable platform for high-resolution exploration of low-energy carrier dynamics in atomically thin materials, opening opportunities for mid-IR optoelectronics and quantum photonics.
Authors
- Sergey G. Kafanov (ORCID: https://orcid.org/0000-0002-7953-101X)
- Rostislav V. Mikhaylovskiy (ORCID: https://orcid.org/0000-0003-3780-0872)
- Rajasekhar Medapalli (ORCID: https://orcid.org/0000-0002-0168-1990)
- Sergio Gonzalez Munoz (ORCID: https://orcid.org/0000-0002-6401-8918)
- A. Patanè (ORCID: https://orcid.org/0000-0003-3015-9496)
- Camilla Coletti (ORCID: https://orcid.org/0000-0002-8134-7633)
- Nils Dessmann (ORCID: https://orcid.org/0000-0003-3005-1098)
- Samuel Jarvis (ORCID: https://orcid.org/0000-0003-4031-1519)
- Vaidotas Mišeikis (ORCID: https://orcid.org/0000-0001-6263-4250)
- Britta Redlich (ORCID: https://orcid.org/0000-0002-7770-9531)
- Khushboo Agarwal (ORCID: https://orcid.org/0000-0001-9384-5229)
- Oleg Kolosov (ORCID: https://orcid.org/0000-0003-3278-9643)
- Nathan D. Cottam (ORCID: https://orcid.org/0000-0002-4367-8044)
- Benjamin T. Dewes
- Wenjing Yan
Institutions
- University of Nottingham (GB)
- Radboud University Nijmegen (NL)
- Shiv Nadar University (IN)
- Center for Nanotechnology Innovation (IT)
- Lancaster University (GB)
Publication Details
- Journal
- Communications Physics
- Published
- 2026-11-03
- DOI
- https://doi.org/10.1038/s42005-026-02954-4
- Primary Topic
- Near-Field Optical Microscopy
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- UK Research and Innovation
- Graphene Flagship
- Defence Science and Technology Laboratory
- Engineering and Physical Sciences Research Council
- Deutsches Elektronen-Synchrotron
- Defence Science and Technology Group