In this work, the time-domain integration of broadband terahertz (THz) pulses via a tapered two-wire waveguide (TTWWG) is reported. Such a guiding structure consists of two metallic wires separated by a variable air gap that shrinks down to a subwavelength size as the movement takes from the waveguide input to its output. It is shown that while an input THz pulse propagates toward the subwavelength output gap, it is reshaped into its first-order time integral waveform. In order to prove the TTWWG time integration functionality, the THz pulse is detected directly within the output gap of the waveguide, so as to prevent the outcoupling diffraction from altering the shape of the time-integrated THz transient. Since the time-domain integration is due to the tight geometrical confinement of the THz radiation in a subwavelength gap volume, the TTWWG operational spectral range can easily be tuned by judiciously changing both the output gap size and the tapering angle. The results lead to the physical realization of a broadband, analog THz time integrator device, which is envisioned to serve as a key building block for the implementation of complex and ultrahigh-speed analog signal processing operations in THz communication systems.

中文翻译：

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锥形两线波导中宽带太赫兹脉冲的时域积分

在这项工作中，报告了通过锥形两线波导 (TTWWG) 对宽带太赫兹 (THz) 脉冲进行时域积分。这种引导结构由两根由可变气隙隔开的金属线组成，随着从波导输入到其输出的运动缩小到亚波长尺寸。结果表明，当输入太赫兹脉冲向亚波长输出间隙传播时，它被重新整形为一阶时间积分波形。为了证明 TTWWG 时间积分功能，在波导的输出间隙内直接检测太赫兹脉冲，以防止外耦合衍射改变时间积分太赫兹瞬变的形状。由于时域积分是由于太赫兹辐射在亚波长间隙体积中的严格几何限制，通过明智地改变输出间隙大小和锥角，可以轻松调整 TTWWG 操作光谱范围。结果导致了宽带模拟太赫兹时间积分器设备的物理实现，该设备被设想为在太赫兹通信系统中实现复杂和超高速模拟信号处理操作的关键构建块。