Abstract
We propose a graphene-based terahertz (THz) photodetector with a microstructure array designed to manipulate the surface electromagnetic modes. Benefiting from the generated localized electromagnetic resonance, a nearly perfect absorption to the incident THz radiation is observed, an asymmetrical temperature distribution is realized along the graphene channel under uniform THz illumination, and thereby an obvious photothermoelectric response is achieved. Polarization and geometry dependence of the photovoltage provides evidence that the photoresponse originated from the localized electromagnetic resonance. Our method is also suitable for other two-dimensional materials and shows promising applications for THz detection.
Highlights
Surface electromagnetic mode, excited by specific structure and material, enables extreme light confinement at subwavelength scale to localize energy in micro-nano volumes and can greatly enhance the interaction between electromagnetic waves and matter [1, 2]
We have proposed a novel graphene THz detector based on PTE effect enabled by the localized electromagnetic resonance (LER) mechanism
The introduction of a LER microstructure enhances the absorption of graphene to THz wave and establishes a global temperature gradient across the graphene device channel even under a uniform illumination
Summary
Surface electromagnetic mode, excited by specific structure and material, enables extreme light confinement at subwavelength scale to localize energy in micro-nano volumes and can greatly enhance the interaction between electromagnetic waves and matter [1, 2]. Taking advantage of the unique properties of LER, i.e., the excellent light absorption and the large intensity of the localized field, the temperature gradient as well as the PTE response can be effectively enhanced [10]. Compared to the traditional PTE photodetectors in which the temperature gradient was realized by nonuniform illumination [11], spatially localized absorption in LER structures results in local heating of the channel material, allowing a uniform or even unfocused optical excitation.
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