No. 01
金刚石钟形探针实现局域驱动光电流的亚波长中红外成像Sub-wavelength mid-infrared imaging of locally driven photocurrents using diamond campanile probes
将中红外（mid-IR）光精确、高效地汇聚到亚波长体积，对于探测低能激发和实现强场增强至关重要，但长波长下的吸收损耗与耦合效率低下阻碍了这一目标。本文提出一种基于金刚石的金属—绝缘体—金属钟形探针，可将自由空间中的中红外光（10 μm）绝热压缩至约0.7 μm的尺度。该探针集成到扫描光电压显微镜中，实现了石墨烯中局域驱动光电流的亚波长成像，在低至约0.1 eV的能量下分辨出偏振相关且对接触敏感的响应。实验揭示出光电流信号密度增强达10 3 倍、光功率耦合效率高于1%、近场光通量密度提高18倍，与数值模拟结果一致。该探针在量子级联激光器和自由电子激光器上的运行表明，它是一个稳健、光谱可调的平台，可用于高分辨率探索原子级薄材料中的低能载流子动力学，为中红外光电子学和量子光子学开辟了机会。
Abstract (English)
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.
Rajasekhar Medapalli, Nathan D. Cottam, Khushboo Agarwal, Benjamin T. Dewes, Nils Dessmann, Sergio Gonzalez-Munoz, Wenjing Yan, Vaidotas Mišeikis, Sergey Kafanov, Rostislav V. Mikhaylovskiy, Samuel P. Jarvis, Camilla Coletti, Britta Redlich, Amalia Patanè, Oleg V. Kolosov
Commun. Phys. (2026)
10.1038/s42005-026-02954-4