基于色散傅里叶变换光子混频的瞬时微波测频技术基础研究

Wide frequency range and high-resolution instantaneous microwave frequency measurement is important and widely used in instantaneous signal acquisition, spectral analysis and processing. Nevertheless, most of photonic-based methods for microwave frequency measurement are confronted with the issue of the trade-off between measurement resolution and measurement frequency range. In recent years, the dual optical frequency comb-based frequency mixing method for microwave frequency measurement, which utilizes optical frequency comb (OFC) characteristics of broadband and electrical characteristics of high-resolution, enables wide measurement frequency range and high measurement resolution, simultaneously. However, it faces the key issues of measurement frequency dead-band and unable multiple-tone microwave frequency measurement. In order to overcome the above issues, a novel photonics mixing-based method for microwave frequency measurement is proposed and demonstrated based on dispersion Fourier transformation. In this project, it enables multiple-tone microwave frequency measurement with wide frequency range, high-resolution and dead-band-free through the same OFC mixing with the under-test microwave signal before and after dispersion Fourier transformation down-conversion, respectively. In our research, the new mechanism of dispersion Fourier transformation-based photonics mixing will be firstly studied and the corresponding theoretical model will be established. Secondly, much attention will be paid to the key technology on how to realize accuracy control of dispersion Fourier transformation, dual OFC-based photonics mixing with single OFC and dead-band-free microwave multiple-frequency recovery. Finally, experiments and optimizations of the proposed microwave frequency measurement will be demonstrated. Our research is believed to promote the technology development of the microwave spectrum measurement with ultra-wide measurement range and ultra-high measurement resolution, and to provide a useful reference for the millimeter-wave or terahertz frequency measurement.

宽频带、高精度的瞬时微波测频在实时信号捕获、频谱分析和处理中具有非常重要的应用。然而，大部分微波光子测频技术存在测量精度与测频范围相互制约的问题。目前，基于双重频光频梳混频的微波测频技术依靠光频梳的宽谱和电谱分析的高精细特性，可同时实现宽频带、高精度的微波测频，却面临测频盲区和无法多音测试的技术难题。为此，本项目拟提出一种基于色散傅里叶变换光子混频的微波测频新方法，利用色散傅里叶变换降频前后的微波信号分别与同一光频梳的光子混频，实现只需单光频梳的面向多音场景的宽频带、高精度、无盲区微波测频。1)探明色散傅里叶变换光子混频的作用机理和理论模型；2)研究基于色散傅立叶变换光子混频的微波测频中色散傅里叶变换精确控制、利用单光频梳实现双光频梳混频、无盲区多音频率恢复等关键技术；3)完成实验验证和性能优化。成果将促进超宽频微波信号高分辨率检测技术的发展，并为探索毫米波乃至太赫兹波的频率测量奠定基础。

瞬时微波测频技术可以实现实时微波信号的捕获、频谱分析和处理，在国防科技、科学研究、工农业生产、日常生活等方面应用非常广泛。传统测频技术面临带宽窄、传输损耗大和易受电磁干扰的问题。微波光子测频技术能有效克服上述电域测频中遇到的问题，实现大瞬时带宽、超宽测频范围以及抗电磁干扰的微波测频，是未来测频技术的发展趋势。.目前，微波光子测频技术虽可对电域测频中所面临的技术难点逐个解决和突破，但难以同时具备高精度、宽频带、多音和无盲区的测频特性。本项目提出了光子混频新技术，实现了超宽带、灵活可调的光子混频，基于此，提出了基于光频梳光子混频的微波测频技术，克服了传统测频技术中存在测频盲区和无法实现多音测频的问题，并且只需单个光频梳和低频探测，结构简单，成本低。此外，还将所提光子混频技术应用于测频链路光电子器件测试分析中，实现了超宽带、高精细的器件特征参量测试。主要内容和结果如下：.（1）在光子混频技术方面：提出了一种基于循环四波混频的光子混频方案，通过将级联四波混频产生的增强谐波反馈到增强模块的输入端，产生宽带、可调光学本振，实现了宽带、可调光子混频；提出了一种基于循环相向频移的光子混频方案，利用电光循环调制移频，调谐循环移频次数以及循环移频步进，实现了灵活可调、宽频范围的光载微波下变频。所提技术，突破了传统光子混频技术的带宽限制，只需低频本振便可实现灵活可调、超宽频带的微波混频。.（2）在微波测频方面：提出了一种基于光频梳光子混频的微波测频方案。通过待测微波信号与两个重复频率不同的光频梳进行光子混频，获得两对混频信号，分析彼此之间频率的交叉互参考关系，实现了高精度、多频的瞬时微波测频，解决了传统双频梳测频技术中存在测量盲区的难题；在此基础上，提出了反馈式单频梳光子混频的微波测频技术，在保证测频性能的前提下，简化测试结构。.（3）在光电子器件测试方面：提出了一种基于光子混频的电光调制器自校准测试方法，通过分析单频梳光子混频成分以及微波去嵌，实现了自校准的高速电光调制器测试；提出了一种基于外差混频的电光调制器测试方案，利用同频、不同驱动电压比的驱动方式，分析混频成分功率比，实现调制系数和半波电压高频特性参量的自校准测试。