光电振荡器的频率稳定化技术研究

发布时间：2018-01-14 02:04

本文关键词：光电振荡器的频率稳定化技术研究　出处：《浙江大学》2017年硕士论文　论文类型：学位论文

【摘要】：微波振荡器是通信、测控、航天、雷达等诸多系统运行的源泉。得益于微波光子学的发展,光电振荡器(optoelectronic oscillator,OEO)自1994年被提出,运用光载射频(RoF)链路及微波反馈回路形成振荡环,可生成频率最高达上百GHz的低相位噪声微波信号,具有巨大的研究价值与广阔的应用前景。然而OEO中所使用的光纤的等效折射率与微波带通滤波器的中心频率对环境温度变化与振动比较敏感,使其频率稳定性有待改善。本文主要对光电振荡器的频率稳定化技术进行了研究。首先对OEO在相位噪声、频率稳定度的研究现状、常用技术进行了介绍,然后分析了OEO的理论模型,包括其阈值条件、振荡功率和频谱特性,研究了传统Yao-Maleki模型未加考虑的闪烁噪声、微波放大器的非线性对OEO系统的影响,对OEO的相位噪声和振荡功率表达式进行了修正和验证。结合上述理论研究,本文针对X波段OEO提出了基于锁相环(PLL)和双自注入锁定(DSIL)以提高OEO频率稳定度的方法。双自注入锁定方法降低了OEO的相位噪声,减少了OEO的频率漂移,并使每个自注入环引入的近载频杂散模式相互抑制。然后设计了PLL电路,实现了DSILOEO与一个100 MHz的恒温晶体振荡器的相位锁定。重点分析了PLL环路传输特性对PLL输出信号的相位噪声的影响,通过优化PLL环路带宽实现了 OEO近载频相位噪声的优化,所得的9.95 GHz信号的相位噪声为-55 dBc/Hz@ 10 Hz和-125dBc/Hz@10kHz,分别在100Hz和10kHz频偏处实现了42 dB和21 dB的抑制,其频率的阿伦方差在平均时间100s处达到7.03 × 10-12,提高了3个数量级。此外,本文在耦合型光电振荡器(COEO)中采用注入锁定-锁相环(IL-PLL)提升了其频率稳定性。通过注入锁定实现OEO振荡频率牵引、锁频以及边模抑制,同时通过与参考源锁相来稳定COEO中的光电振荡环路,使注入锁定状态易于保持。理论分析了IL-PLL对振荡器的作用原理,然后通过实验验证了IL-PLL方法对COEO频率稳定性的提升,所得信号相位噪声为-72dBc/Hz@10Hz,-103dBc/Hz@1kHz 及-121dBc/Hz@10kHz,频率的阿伦方差在平均时间100 s处为6.41 × 10-12。
[Abstract]:Microwave oscillator is the source of communication, measurement and control, spaceflight, radar and so on, which benefit from the development of microwave photonics. Optoelectronic oscillator (OEO) has been proposed since 1994. The low phase noise microwave signal with a maximum frequency of hundreds of GHz can be generated by using the optical RF RF link and the microwave feedback loop to form an oscillatory loop. However, the equivalent refractive index of fiber used in OEO and the center frequency of microwave band-pass filter are sensitive to the change of ambient temperature and vibration. In this paper, the frequency stabilization technology of optoelectronic oscillator is studied. Firstly, the research status of phase noise and frequency stability of OEO is introduced. Then, the theoretical model of OEO is analyzed, including its threshold condition, oscillation power and spectrum characteristics, and the scintillation noise which is not considered in the traditional Yao-Maleki model is studied. The influence of nonlinear microwave amplifier on OEO system is studied. The phase noise and oscillatory power expressions of OEO are modified and verified. In this paper, based on phase-locked loop (PLL) and dual-self-injection locking (DS-L), a novel X-band OEO is proposed. In order to improve the frequency stability of OEO, the dual self-injection locking method reduces the phase noise of OEO. The frequency drift of OEO is reduced and the near-carrier spurious mode introduced by each self-injection loop is suppressed. Then the PLL circuit is designed. The phase locking between DSILOEO and a 100 MHz constant temperature crystal oscillator is realized. The effect of transmission characteristics of PLL loop on the phase noise of PLL output signal is analyzed. The OEO near-carrier frequency phase noise is optimized by optimizing the PLL loop bandwidth. The phase noise of the 9.95 GHz signal is -55 dBc/Hz@10 Hz and -125 dBc / Hz 10 kHz. 42 dB and 21 dB were suppressed at 100 Hz and 10 kHz frequency offset, respectively. The aron variance of the frequency reached 7.03 脳 10 ~ (-12) at the average time of 100 s. Increased by three orders of magnitude. In this paper, the frequency stability of the coupled optoelectronic oscillator (COEO) is enhanced by injection lock-phase locked loop (IL-PLL), and the OEO oscillation frequency traction is realized by injection locking. The frequency locking and edge mode suppression are used to stabilize the optoelectronic oscillation loop in COEO by combining with the reference source phase lock, which makes the injection locking state easy to maintain. The working principle of IL-PLL to the oscillator is analyzed theoretically. Then the IL-PLL method is proved to improve the frequency stability of COEO. The phase noise of the signal is -72 dBc / Hz @ 10Hz. 103dBc / HzR @ 1kHz and -121dBc / Hzr / Hz@ 10kHz, the Aron variance of the frequency is 6.41 脳 10-12 at an average time of 100s.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN752

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