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 can be hindered by absorption losses and coupling inefficiencies at long wavelengths. Here, we introduce an innovative diamond-based metal-insulator-metal campanile probe that adiabatically compresses free-space mid-infrared light (10 μm) into ≈1 µm domains. 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 10³ and coupling efficiencies approaching 80%, 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.

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 can be hindered by absorption losses and coupling inefficiencies at long wavelengths. Here, we introduce an innovative diamond-based metal-insulator-metal campanile probe that adiabatically compresses free-space mid-infrared light (10 μm) into ≈1 µm domains. 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 10³ and coupling efficiencies approaching 80%, 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.

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 can be hindered by absorption losses and coupling inefficiencies at long wavelengths. Here, we introduce an innovative diamond-based metal-insulator-metal campanile probe that adiabatically compresses free-space mid-infrared light (10 μm) into ≈1 µm domains. 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 10³ and coupling efficiencies approaching 80%, 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.

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 can be hindered by absorption losses and coupling inefficiencies at long wavelengths. Here, we introduce an innovative diamond-based metal-insulator-metal campanile probe that adiabatically compresses free-space mid-infrared light (10 μm) into ≈1 µm domains. 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 10³ and coupling efficiencies approaching 80%, 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.