Terahertz (THz) and sub-THz frequency emitter and detector technologies are receiving increasing attention, underpinned by emerging applications in ultra-fast THz physics, frequency-combs technology and pulsed laser development in this relatively unexplored region of the electromagnetic spectrum. In particular, semiconductor-based ultrafast THz receivers are required for compact, ultrafast spectroscopy and communication systems, and to date, quantum-well infrared photodetectors (QWIPs) have proved to be an excellent technology to address this, given their intrinsic picosecond-range response. However, with research focused on diffraction-limited QWIP structures ($\lambda /2$), RC constants cannot be reduced indefinitely, and detection speeds are bound to eventually meet an upper limit. The key to an ultra-fast response with no intrinsic upper limit even at tens of gigahertz (GHz) is an aggressive reduction in device size, below the diffraction limit. Here we demonstrate sub-wavelength ($\lambda /10$) THz QWIP detectors based on a 3D split-ring geometry, yielding ultra-fast operation at a wavelength of around 100 μm. Each sensing meta-atom pixel features a suspended loop antenna that feeds THz radiation in the $\sim 20{\mathrm{\mu m}}^3$ active volume ($V_{\mathrm{eff}}\sim 3\times {10}^{-4}{(\lambda /2)}^3$). Arrays of detectors as well as single-pixel detectors have been implemented with this new architecture, with the latter exhibiting ultra-low dark currents below the nA level. This extremely small resonator architecture leads to measured optical response speeds—on arrays of 300 devices—of up to $\sim 3\mathrm{GHz}$ and an expected device operation of up to tens of GHz, based on the measured $S$ parameters on single devices and arrays.

中文翻译：

---

基于三维亚原子的超快太赫兹探测器

太赫兹（THz）和次THz频率发射器和检测器技术正受到越来越多的关注，这是由于超快THz物理的新兴应用，频率梳技术以及在电磁频谱这个相对未开发的区域中的脉冲激光器的发展所致。特别是，紧凑，超快光谱和通信系统需要基于半导体的超快THz接收器，并且迄今为止，鉴于量子阱红外光电探测器（QWIP）固有的皮秒范围响应，它已被证明是解决这一问题的出色技术。但是，研究集中在衍射受限的QWIP结构上（$\lambda /\mathrm{2个}$），RC常数不能无限降低，并且检测速度必然会最终达到上限。即使在数十千兆赫（GHz）时也没有固有上限的超快速响应的关键是要积极缩小器件尺寸，使其低于衍射极限。在这里，我们演示了亚波长（$\lambda /10$）基于3D开口环几何形状的THz QWIP检测器，可在100μm左右的波长下实现超快操作。每个感应的亚原子像素都具有一个悬挂式环形天线，该环形天线在THz辐射中馈入THz辐射。$〜20{\mathrm{微米}}^3$ 有效音量（${\mathrm{伏特}}_{效}〜3\times {10}^{-4}{（\lambda /\mathrm{2个}）}^3$）。检测器阵列以及单像素检测器已通过这种新架构实现，后者具有低于nA电平的超低暗电流。这种极小的谐振器架构导致在300个设备的阵列上测得的光学响应速度高达$〜3\mathrm{兆赫}$ 根据测得的结果，预期的设备工作频率可达数十GHz $\mathrm{小号}$ 单个设备和阵列上的参数。