【作者】 孙杰；

【导师】 万文杰；

【作者基本信息】 上海交通大学 ， 物理学， 2021， 硕士

【摘要】 太赫兹技术是当前热门的研究领域之一,在通信,物联网技术,生物和医学研究,食品和农产品的质量检测等领域具有广泛的应用。太赫兹探测技术在太赫兹研究领域中占有重要地位,当前主要的太赫兹探测器类型有热释电探测器、半导体辐射热计、超导SIS混频器等。随着太赫兹探测技术的飞速发展以及应用前景日益广泛,太赫兹探测器需要具备较高的灵敏度、较低成本以及能够在室温下工作等特点以满足多种应用场景。本文提出了一种新颖的基于非线性和频过程的太赫兹间接探测方案,通过非线性和频过程将太赫兹波上转换到光波段,利用光电探测器直接探测生成的光波,从而间接探测到太赫兹波。为了解决太赫兹信号源功率较小引起的非线性过程效率较低等问题,我们在非线性晶体中内置有金天线,它可以同时增强光波和太赫兹波,提升和频过程的有效转换效率。我们利用有限元方法(FEM)对光波和太赫兹波在天线中的增强做了仿真模拟,并且研究了天线的几何形状对电场增强的影响,设计合适的天线结构用于增强在和频过程中相互作用的光波和太赫兹波。我们的天线增强方案可以用于增强非线性过程,具有广阔的光学应用前景。为了评估太赫兹探测方案的效果,我们利用时域有限差分方法(FDTD)对和频过程开展仿真模拟,通过和商用太赫兹探测器进行对比发现,我们的探测系统在室温下的噪声等效功率(NEP)更低。我们的探测方案结构较为简单,具有可以在室温下工作、探测带宽较宽、噪声等效功率较低等优点,为研制高性能的太赫兹探测器提供了一种具有可行性的实验方法。此外,我们的装置将光频域和太赫兹频域相结合,因此它可以用于将太赫兹无线链路集成到光链路中,以助力未来无线通信的发展。更多还原

【Abstract】 Terahertz technology is one of the current popular research fields,which has a wide range of applications in communication,Internet of Things,biological and medical research,food and agricultural product quality testing and other fields.Terahertz detection technology plays an important role in terahertz research.The current main types of terahertz detectors include pyroelectric detectors,semiconductor bolometers,and superconducting SIS(Superconductor-Insulator-Superconductor)mixers,etc.With the rapid development of terahertz detection technology and the increasingly broad application prospects,the terahertz detectors in future need to have higher sensitivity,lower cost and be able to work at room temperature to satisfy diverse application scenarios.We propose a novel terahertz indirect detection scheme based on the nonlinear sum frequency generated(SFG)process.The terahertz wave is up-converted to the optical band through the SFG process,and the terahertz wave is detected indirectly by using photodetector to detect the generated optical wave directly.In order to solve the problems such as low efficiency of the nonlinear process caused by low power of the terahertz signal source,we built a gold antenna in the nonlinear crystal,which can enhance the optical wave and the terahertz wave at the same time and improve the effective conversion efficiency of the SFG process.We simulated the enhancement of optical waves and terahertz waves illuminating on the antenna with finite element method(FEM),and studied the influence of antenna geometry on electric field enhancement,and designed the suitable antenna structure to enhance the optical wave and terahertz wave interacting in the SFG process.Our antenna enhancement scheme can be used to enhance the nonlinear process and has broad prospects for optical applications.In order to evaluate the effect of the terahertz detection scheme,we simulated the SFG process with finite-difference time-domain(FDTD)method.By comparing with commercial terahertz detectors,it is found that our detection system has lower noise-equivalent power(NEP)at room temperature.Our detection scheme has a relatively simple structure and has the advantages of being able to work at room temperature,wider detection bandwidth,and lower NEP.It provides a feasible experimental method for the development of high-performance terahertz detectors.In addition,our device combines the optical domain and the terahertz domain,so it can be used to integrate terahertz wireless link into optical link to facilitate the development of future wireless communication.更多还原