High-sensitivity broadband THz surface plasmon polariton detector for communication and imaging

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Terahertz (THz) detectors operating at room temperature with high sensitivity, broadband spectral response, and compact structure are crucial for emerging applications such as wireless communications and imaging. This work proposes a semiconductor surface plasmon polariton (SPP) InSb THz detector utilizing a double-slot-antenna-assisted ohmic metal-semiconductor-metal (OMSM) structure. The OMSM design eliminates nonlinear Schottky barriers, ensuring the photoresponse is purely dominated by SPP-induced transport for highly efficient carrier collection. Compared to dipoles, the double-slot antenna exhibits superior electromagnetic field focusing for free-space THz radiations, achieving a high normalized electric field intensity enhancement ( E 2 / E 0 2 ) of up to 2107. Finite element simulations reveal significant electric field enhancement and SPP excitation at the interfaces, driving strong non-equilibrium carrier generation. Through a systematic design process of scaling antenna dimensions based on Babinet’s principle, high sensitivity is achieved across a broad 26.5–500 GHz band. At 165.4 GHz, the optimal detector achieves a peak responsivity of 8.2×10 4 V W −1 , a noise-equivalent power of 1.22×10 −13 W Hz −1/2 , a specific detectivity of 1.48×10 12 Jones, and a polarization extinction ratio of 7.1:1. Leveraging its high sensitivity and relatively fast response, we successfully demonstrate proof-of-concept binary communication and single-pixel THz imaging, highlighting the detector’s potential for high-performance THz systems.