Terahertz source frequency comb based on difference frequency generation from a mid-IR quantum cascade laser

基于中红外量子级联激光器差频生成的太赫兹源频率梳

• 批准号: 1505409
• 负责人: Manijeh Razeghi
• 金额: $ 36万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-05-01 至 2018-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1505409&HistoricalAwards=false
• 关键词: Terahertz; source; frequency; comb; based

Compact, Chip-based Terahertz Frequency CombAbstractNon-techniical: A frequency comb is a light source whose spectrum consists of a series of discrete, equally spaced elements. Since their discovery in the 1990s, frequency combs have revolutionized metrology, spectroscopy, and frequency synthesis with extraordinary precision and speed. However, spectroscopic applications are limited by the wavelength range that is accessible by the comb. The terahertz (THz) spectral range, where abundant molecules have strong spectral fingerprints or feature broad absorption bands, is not easily accessible with current comb technology. The main challenge is the need for multiple optical components or cryogenic cooling, which leads to a complicated and expensive source. A novel approach is proposed to develop a chip-based THz frequency comb source operating at room temperature. This simple to use and compact source will be an enabling technology which will allow easy access to THz spectroscopy/ imaging for the broader scientific community. Technical: The objective of the proposed research is to demonstrate a room temperature, continuous wave, monolithic THz frequency comb source with sub-milliwatt level output power. The approach is to use a mid-IR quantum cascade laser (QCL) engineered with a flat-top gain and large 2nd and 3rd order optical nonlinearities for the intracavity difference frequency generation (DFG) of a THz frequency comb. A dual-section cavity design is proposed to render the mid-infrared pump source with an output exhibiting a unique combination of single- and multi-mode operation. The multi-mode output can be locked to equally spaced comb modes via four wave mixing and an engineered near-zero group velocity dispersion. Such a cavity scheme provides the perfect conditions for creating a THz comb output via the DFG process and a broadband Èerenkov phase matching scheme. In contrast to a mode-locked laser comb source, which is bulky and expensive, the proposed THz comb source offers a monolithic solution that, once developed, has potential for cost-effective mass production using the existing semiconductor laser fabrication infrastructure. This project is an excellent example of a multidisciplinary approach used to circumvent existing technological limitations. Solid state physics, material science, nonlinear optics, and laser physics are all major components of the research plan, which are all supported generally by NSF, and are used, in this case, together to combine multiple functional elements into a single, compact, high power device.

摘要非技术性的：频率梳是一种光源，其光谱由一系列离散的、等间距的元素组成。自20世纪90年代被发现以来，频率梳以非凡的精度和速度彻底改变了计量学、光谱学和频率合成。然而，光谱应用是有限的，是由梳访问的波长范围。太赫兹（THz）光谱范围，其中丰富的分子具有强的光谱指纹或功能宽的吸收带，是不容易与当前的梳技术。 主要的挑战是需要多个光学元件或低温冷却，这导致了复杂和昂贵的光源。 提出了一种基于芯片的室温太赫兹梳状频率源的研制方法。这种简单易用的紧凑型光源将成为一种使能技术，使更广泛的科学界能够轻松获得THz光谱/成像。 技术支持：提出的研究的目的是展示一个室温，连续波，单片太赫兹频率梳状源与亚毫瓦级输出功率。该方法是使用一个中红外量子级联激光器（QCL）工程与平顶增益和大的第二和第三阶光学非线性的太赫兹频率梳的腔内差频产生（DFG）。提出了一种双段腔设计，使中红外泵浦源的输出呈现出独特的组合的单模和多模操作。多模输出可以通过四波混频和工程化的近零群速度色散锁定到等间隔的梳状模。这样的腔方案提供了通过DFG过程和宽带Schierenkov相位匹配方案产生THz梳状输出的完美条件。与体积庞大且昂贵的锁模激光梳状源相比，所提出的太赫兹梳状源提供了单片解决方案，一旦开发出来，就有可能使用现有的半导体激光器制造基础设施进行成本效益高的大规模生产。这一项目是一个很好的例子，说明采用多学科方法来规避现有的技术限制。固态物理学、材料科学、非线性光学和激光物理学都是研究计划的主要组成部分，它们都得到了NSF的普遍支持，在这种情况下，它们一起用于将多个功能元件联合收割机组合成一个单一的、紧凑的、高功率的设备。