Resonant tunneling diodes (RTDs) provide room-temperature terahertz oscillation and strong nonlinear mixing, enabling compact monostatic sensors in which a single device acts as both a bias-tunable oscillator and a self-oscillating mixer. This paper presents a 280 GHz-band radar concept enabled by a single RTD, which exploits self-mixing to generate a low-frequency radar interferometric signal while sweeping the RTD oscillation frequency. We show that the RTD self-mixing waveform can be interpreted from a radar perspective and processed to extract micrometer-scale displacement and thin-film thickness changes from repeated sweeps. Using the proposed technique, we experimentally demonstrate a minimum detectable displacement of ~5 um and quantitatively resolve polymer film thicknesses of 12.5, 25, and 50 um.

翻译：谐振隧穿二极管（RTD）可在室温下实现太赫兹振荡并具备强非线性混频特性，从而支持紧凑型单站传感器设计，其中单个器件同时作为偏压可调振荡器与自振荡混频器。本文提出一种由单个RTD实现的280 GHz频段雷达方案，该方案利用自混频在扫描RTD振荡频率的同时生成低频雷达干涉信号。我们证明，RTD自混频波形可从雷达角度进行解析，并通过处理重复扫描数据来提取微米级位移与薄膜厚度变化。采用所提技术，我们通过实验实现了约5微米的最小可检测位移，并定量解析了12.5、25及50微米厚度的聚合物薄膜。