【作者】 乔云飞；

【导师】 章献民；

【作者基本信息】 浙江大学 ， 电子科学与技术， 2013， 博士

【摘要】 微波光子学是一门新兴的研究微波信号与光信号相互作用的交叉学科,其研究领域包括了微波信号的光子学产生、传输、测量与处理,光纤无线通信系统,光控相控阵雷达等。基于微波光子技术的宽带、可调谐微波／毫米波信号产生作为微波光子系统中的一项关键技术,近年来吸引了广泛关注。论文简要介绍了微波光子学的发展历史及主要应用领域,围绕基于微波光子学的宽带可调谐微波／毫米波信号源,从理论分析和实验验证两方面,研究了几种性能优越、结构新颖的微波／毫米波产生方案,分别为基于光倍频的可调毫米波信号源、基于倍频光电振荡器的可调微波信号源和基于微片激光器的可调微波信号源。基于光自外差原理的光倍频毫米波产生技术是通过对低频信号的光域处理来产生高频毫米波信号。该方案对器件要求低,性价比较高。论文通过构建一个多次调制的光纤环形腔,结合可调光滤波器,实现了10GHz微波信号的光学6次倍频,获得了60GHz的毫米波信号,并通过改变低频调制信号的频率实现了毫米波信号频率的可调。基于倍频光电振荡器的可调微波信号源具有极低的相位噪声和极高的频谱纯度。论文在深入研究光电振荡器相关理论基础上,提出了一种基于相位调制器和啁啾光纤光栅的倍频光电振荡器结构,该方案利用一个级联了光带通滤波器的相位调制器实现双边带相位调制,经拍频产生倍频信号,同时通过啁啾光纤光栅的色散效应产生驱动调制器的基频反馈信号。实验中成功获得高质量的8GHz基频信号和16GHz倍频信号。在该方案基础上,去除啁啾光纤光栅,代之以受激布里渊散射的选择性放大来获得基频反馈信号以构成振荡环路。通过改变布里渊散射的泵浦信号,就可实现了倍频光电振荡器输出信号的频率调节。实验中使用载波抑制的强度调制信号作为布里渊泵浦,当低频驱动信号频率在200MHz～2GHz范围变化时,可获得一个在21.4-25GHz范围内连续变化的倍频微波信号。基于微片激光器的可调微波信号源具有成本低、体积小、性能高和宽带调谐的优点,可满足未来通信系统对集成度的要求,是目前的研究热点,也是本文研究的一个重点。论文系统研究了基于微片激光器的可调微波信号源。在理论分析微片激光器基础上,设计并研制了Nd:YAG+LiNbO3复合腔微片激光器,其中Nd:YAG作为激光增益介质,LiNbO3作为电光调谐介质,并通过合理的泵浦使得谐振腔运行在基横模状态,保证其单模输出。通过改变加在电光晶体LiNbO3上的直流控制电压,由腔内双折射效应获得的相互正交的双频激光经拍频后即可产生频率连续线性可调的宽带微波信号。由于腔内两个正交激光模式是由同一个谐振腔产生,经历相同的相位波动、具有很好的相位相干性,因此拍频得到的微波信号具有很好的相位噪声性能。本方案实现的可调微波信号源具有结构紧凑、易于集成、调节带宽大、响应速度快、控制简单及信号质量高等优点。实验实现了调节灵敏度为3.02MIlz/V、最大输出频率14GHz的系统性能,其中14GHz信号在10kHz偏移处的相位噪声约为-82dBc/Hz。更多还原

【Abstract】 Microwave photonics is an emerging interdisciplinary research area which studies the interaction of microwave and optical signals for applications such as photonic generation, distribution, processing and measurement of microwave/millimeter-wave signal; radio-over-Fiber (RoF) system; optically controlled phased array radar, and so on. As a key technique for microwave photonic system, generation of wideband and tunable microwave signal has attracted great interests in the past few years. With briefly introducing the historical development and main application areas of microwave photonics, this thesis is mainly concerned on the generation of widely tunable microwave/millimeter-wave signal based on microwave photonics, and propose several novel methods both theoretically and experimentally, including microwave source based on optical frequency multiplication (OFM); tunable microwave source based on frequency-doubling optoelectronic oscillator (OEO) and microwave source based on microchip laser.The OFM generation of millimeter wave signal based on optical self-heterodyning, generating high frequency millimeter wave signal through processing low frequency signal in optical domain, has low requirement for device and high cost performance. By configuring a fiber ring resonator combined with an tunable optical filter, a60GHz millimeter wave with six-time frequency multiplication of a lOGHz microwave signal is obtained, while the frequency tenability can be realized by adjusting the frequency of driven signal.The tunable microwave source based on frequency-doubling OEO has excellent phase noise performance. After fully studying the principle of OEO, we first propose a simple realization of frequency-doubling optoelectronic oscillator using a phase modulator and a chirp fiber Bragg grating (CFBG). In this OEO configuration, a phase modulator in combination with an optical filter is working as doubled-sideband phase modulation to produce a frequency-doubling microwave signal, while the CFBG ensures the oscillation of feedback driving signal at fundamental frequency with its dispersion effect. As a result, high quality fundamental signal at8GHz and frequency-doubling signal at16GHz are simultaneously obtained. Furthermore, on the basis of frequency-doubling optoelectronic oscillator mentioned above, removing the CFBG, we introduce Stimulated Brillouin Scattering effect to provides the narrowband filtering and ensure the oscillation of the feedback driving signal at fundamental frequency. By varying the Brillouin pump signal introduced via double sideband-carrier suppression (DSB-CS) modulation, the frequency tunability of the frequency-doubling OEO is realized over a wide range. In experiment, a continuous tunable frequency-doubling signal from21.4GHz to25GHz is generated when the diving signal applied on the intensity modulator is tuned from200MHz to2GHz.The tunable microwave source based on microchip laser, which has the advantages of low cost, compact size, high performance and wideband tenability, and can effectively meet the need of integration for future communication system, is not only a hot spot for research, but also a focus of this thesis. We fully investigating the principle of microchip laser, design and fabricate a composite cavity microchip laser, which consists of Nd.YAG crystal acting as active medium and LiNbO3acting as electro-optical tuning component. Varying the controlling voltage applied on the LiNbO3, a continuously tunable microwave signal can be easily obtained by beating the dual-frequency laser with two orthogonal polarization modes that generated by the intra-cavity birefringence. Because the two optical modes share the same cavity and experience the same phase fluctuations, a good phase noise performance heterodyning signal is expected due to the good phase coherence. This configuration has several unique advantages, such as compact size, flexible integration, wideband tunability, high respond speed and excellent signal quality. In experiment, a widely electrically tunable microwave source with tuning range of14GHz and tuning sensitivity of3.02MHz/V is demonstrated, while the phase noises of14GHz signals is about-82dBc/Hz.更多还原