A terahertz spectrometer on a chip, at the thermodynamical limits

芯片上的太赫兹光谱仪，处于热力学极限

• 批准号: 1810506
• 负责人: Chee Wei Wong
• 金额: $ 39万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-01 至 2022-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1810506&HistoricalAwards=false
• 关键词: terahertz; spectrometer; chip; thermodynamical; limits

Terahertz spectrometry offers a platform for long-distance and non-destructive detection of trace chemicals and gases, explosives, pathogens, and biological agents. These molecules and hazardous agents have unique absorption spectra in the terahertz frequencies, enabling identification of concealed hazardous substances from remote distances. Heterodyne spectrometers are at the frontier for high spectral resolution terahertz spectrometry. Achieved through a number of different techniques such as nonlinear frequency mixing in Schottky diodes, superconductor-insulator-superconductor structures, or hot electron bolometers, they have linewidth-to-center frequency ratios down to one part in a million. These state-of-the-art heterodyne spectrometers and mixers, however, are bulky (weighing tens of kilograms), are bounded by electronic noise far from the fundamental noise limits, and often require cryogenic cooling to reach appreciable sensitivities. This project proposes a chip-scale terahertz spectrometer based on modular integration of a chip-scale laser frequency comb with a chip-scale photomixer. The laser frequency comb consists of discrete optical frequency lines, widely tunable over an octave. The photomixer is based on a plasmonically-enhanced absorbing substrate, directly coupled to a terahertz antenna to collect the incident terahertz radiation. The proposed single-chip terahertz receiver has spectrometry bandwidth of 1-8 THz with spectral resolution better than a kHz, and operates close to the thermodynamical noise limits. The high-performance, low-cost, and compact terahertz spectrometer brings valuable applications in space sciences, biological analysis, environmental studies, pharmaceuticals, and industrial quality control. The proposed scientific efforts are coupled with an outreach and education plan. This involves outreach to underrepresented high-school students and teachers, improvements to the graduate and undergraduate curriculum, and outreach to the general public with focus on underrepresented women and minority students in summer research experiences for undergraduates. The proposed advancement on the heterodyne chip-scale spectrometer consists of three cross-related Thrusts. In Thrust 1, the project will demonstrate an on-chip frequency comb oscillator with wide tuning range of 1-8 THz and comb line-to-line non-uniformity at 0.2 parts per quadrillion when referenced to the optical carrier. In Thrust 2, the project will develop an on-chip integrated pump laser and amplifier, for heterogeneous integration with the photomixer and frequency comb. In Thrust 3, the project will demonstrate the integrated chip-scale heterodyne receiver based on an antenna-coupled plasmonic photomixer. The team seeks to measure a heterodyne photomixer with double-sideband noise sensitivities close to the fundamental bound. The frequency-agile approach is enabled by their recent preliminary studies and measurements close to or at the thermodynamical noise limits. The proposed terahertz spectrometry architecture and scientific Thrusts can transform the platform of terahertz waves for atmospheric studies, space explorations, and safety-industrial-environmental quality control systems. The scientific Thrusts are integrated with educational outreach and cross-disciplinary training efforts. This three-year project will educate a new generation of scientists at the interface of precision chip-scale frequency combs and plasmonic photomixers for transformative terahertz spectrometry near the fundamental bounds.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

Terahertz光谱法提供了一个平台，用于长距离和非破坏性检测痕量化学物质和气体，炸药，病原体和生物学剂。这些分子和危险剂在Terahertz频率中具有独特的吸收光谱，从而可以鉴定出远距离隐藏的危险物质。杂源光谱仪位于高光谱分辨率Terahertz光谱法的边界。通过多种不同的技术，例如在Schottky二极管，超导体 - 绝缘体 - 渗透率结构或热电子验证仪中的非线性频率混合，它们具有线宽到中心的频率比在一百万中降至一部分。然而，这些最先进的杂质光谱仪和混合器是笨重的（重量数十公斤），受电子噪声远离基本噪声限制的界定，并且通常需要低温冷却以达到明显的敏感性。该项目提出了一个基于芯片尺度激光频率梳子与芯片尺度摄影仪的模块化整合的芯片尺度terahertz光谱仪。激光频率梳由离散的光频线组成，可在八度上广泛调谐。光质子基于血浆增强的吸收底物，直接与Terahertz天线耦合以收集入射Terahertz辐射。所提出的单芯片Terahertz接收器的光谱带宽为1-8 THz，光谱分辨率比KHz更好，并且接近热力学噪声限制。高性能，低成本和紧凑的Terahertz光谱仪在太空科学，生物分析，环境研究，药物和工业质量控制中带来了宝贵的应用。拟议的科学努力与外展和教育计划相结合。这涉及向代表性不足的高中生和老师提供宣传，改善研究生和本科课程，并向公众推广，以专注于本科生的夏季研究经历，以专注于代表性不足的妇女和少数族裔学生。杂化芯片尺度光谱仪的拟议进步由三个与交叉相关的推力组成。在推力1中，该项目将展示一个芯片频率梳子振荡器，其宽度调谐范围为1-8 THz，并在梳子线对线的不均匀度为0.2零件时，每四十四零件参考光载体。在推力2中，该项目将开发一个片上集成的泵激光器和放大器，以与光质和频率梳子进行异质整合。在推力3中，该项目将基于天线耦合的等离子光质子来证明集成的芯片尺度杂差接收器。该团队试图测量具有双侧噪声敏感性接近基本界限的杂化摄影仪。频率敏捷方法是通过其最近的初步研究和接近或热力学噪声限制的测量值来实现的。提出的Terahertz光谱架构和科学推力可以改变Terahertz波的平台，以进行大气研究，太空探索和安全 - 工业 - 环境质量控制系统。科学推力与教育外展和跨学科培训工作融合在一起。这个为期三年的项目将通过精密芯片尺度频率梳子和等离子镜片的界面进行新一代科学家的教育，以在基本界限附近进行变革性的Terahertz光谱法。该奖项反映了NSF的法定任务，并通过该基金会的知识分子优点和广泛的影响来评估NSF的法定任务。