We present a photoconductive terahertz detector that employs a plasmonic nanocavity to offer high-sensitivity and broadband operation when used in a terahertz time-domain spectroscopy system even at very low optical pump power levels. By employing a plasmonic nanocavity, all of the photocarriers are generated within a 100 nm distance from the photoconductor contact electrodes, enabling a short transport time for almost all of the photogenerated carriers. As a result, the photoconductive detector maintains high quantum efficiency and ultrafast operation simultaneously, enabling high-sensitivity and broadband operation at very low optical pump power levels. We utilize a photoconductive detector based on a plasmonic nanocavity optimized for operation at a 770 nm optical wavelength in a terahertz time-domain spectroscopy system and demonstrate a 100 dB signal-to-noise ratio and a 0.1–6 THz noise-equivalent bandwidth at a record-low average optical pump power of 0.1 mW, compared to the state-of-the-art photoconductive terahertz detectors. The extremely low optical power budget of the demonstrated photoconductive detector makes this detector attractive for multi-pixel terahertz imaging systems.

中文翻译：

---

通过等离子体纳米腔中的光子捕获进行高效光电导太赫兹检测

我们提出了一种光电导太赫兹探测器，它采用等离子体纳米腔，在太赫兹时域光谱系统中使用时，即使在非常低的光泵功率水平下也能提供高灵敏度和宽带操作。通过采用等离子体纳米腔，所有光载流子都在距离光电导体接触电极 100 nm 的范围内产生，从而使几乎所有光生载流子的传输时间都缩短。因此，光电导探测器同时保持高量子效率和超快运行，在非常低的光泵功率水平下实现高灵敏度和宽带运行。我们利用基于等离子体纳米腔的光电导探测器在太赫兹时域光谱系统中优化了在 770 nm 光波长下运行，并展示了 100 dB 的信噪比和 0.1-6 THz 噪声等效带宽与最先进的光电导太赫兹探测器相比，平均光泵功率为 0.1 mW，创历史新低。所展示的光电导探测器极低的光功率预算使该探测器对多像素太赫兹成像系统具有吸引力。