【作者】 倪娟；

【导师】 章献民；

【作者基本信息】 浙江大学 ， 电磁场与微波技术， 2011， 博士

【摘要】 微波光子学是一门集合了微波技术和光通信优势的交叉学科,利用光子学的办法处理微波信号,具有传输损耗低、带宽高、抗干扰能力强等优点。光纤光栅的出现,因其频谱的多样性和应用的灵活性,已成为微波光子学应用中一个重要的光纤器件,它在光载无线系统、微波/毫米波信号源、光控相控阵天线、光子微波信号处理等多个领域具有很好的应用前景。本论文主要研究的是光纤光栅在微波光子学中的应用：基于π-相移光纤Bragg光栅改善RoF链路性能。使用窄线宽的相移光纤光栅作为光滤波器抑制光载波改善RoF链路性能。载波抑制后,链路增益和噪声系数提高了17dB,动态范围也得到了明显提高,得到的射频功率曲线在4-14 GHz范围内浮动不超过2 dB。基于窄带光纤光栅和布里渊掺铒光纤激光器来实现60 GHz毫米波。布里渊光纤激光器产生第n阶斯托克斯光,经过窄带光纤光栅滤波以后,与泵铺光一起送到高速光电探测器上拍频,得到了毫米波信号,该方法无需外部微波信号源。基于π-相移光纤Bragg光栅实现可调谐超宽带陷波滤波器。滤波器的3 dB通带在3.1～10.6 GHz,陷波中心波长在5.5 GHz附近,最大的陷波点功率减少了25 dB以上,有效减少了与IEEE802.11a无线通信之间的信号干扰。基于光纤光栅和相位调制器进行实时频率测量,光调制信号的载波位于光纤光栅斜边的不同位置时,得到了不同的微波功率,通过频率与功率的映射关系得到微波信号的频率。系统仅需要一个光纤光栅,简化了实验结构,且提高了频率可测量范围和精度。相比强度调制器,相位调制器插入损耗小,而且不需要直流偏置,系统更加稳定。更多还原

【Abstract】 Microwave photonics is an interdisciplinary area, which combines the advantages of microwave technology and optical communication. Processing the microwave signals with photonic techniques has many advantages, such as low cost, high bandwidth, immunity to electromagnetic interference ect. The fiber Bragg grating(FBG) is a key component for the applications in microwave photonics, for its diversity of the spectrum and flexibility. It can be used in radio over fiber technology, microwave/millimeter-wave generation, phased-array radar and photonics signal processing, etc. In this thesis, the applications of FBGs in microwave photonics are studied:A low-cost method for improving RoF performances by using a phase-shift fiber Bragg grating is proposed. The fiber grating with an ultra-narrow bandwidth is implemented as an optical filter, to suppress the optical carrier of the double-sideband signal. Experimental results show that 17 dB improvement of the RoF link gain and noise figure can be achieved after the carrier suppression. The spur-free dynamic range can also be significantly improved. As a result, the RF gain response is flat with fluctuation less than 2dB ranging from 4 GHz to 14 GHz.A novel system configuration is introduced for optical generation of 60GHz millimeter wave, which is realized through Brillouin-erbium fiber laser and a fiber Bragg grating. The nth-order Stokes wave is generated in the Brillouin-erbium fiber laser, and filtered out by the fiber Bragg grating. The microwave/mm-wave is generated by the mixing of the nth-order Stokes wave and the pump power on the high-speed photodetector.60GHz millimeter wave is generated without any microwave generator.A novel tunable ultra-wideband bandpass filter with narrow notched band is proposed based on a phase-shift fiber Bragg grating. The proposed filter ranges from 3.1 to 10.6 GHz with the center frequency of narrow notched band located at about 5.5 GHz. The rejection loss is more than 25 dB at the dip of the notched band. It can avoid interference that occurs with IEEE 802.11a radio signals significantly. Instantaneous microwave frequency measurement based on frequency-to-power mapping is proposed and demonstrated by using the transmission spectrum of a FBG. The microwave frequency can be estimated by measuring the microwave power difference when the carrier located at the different positions of the FBG. The entire system was significantly simplified and cost-effective since only a FBG was used. Microwave frequency measurement with improved measurement range and resolution is realized. In addition, the optical phase modulator has smaller insertion loss, and can be worked without the bias circuit, so the system is more stable by using an optical phase modulator than Mach-Zehnder intensity modulator.更多还原