微波信号光学产生与调制方法研究

发布时间：2018-01-25 13:56

本文关键词： 微波信号 Sagnac干涉仪可调频率相位调制器脉冲压缩比　出处：《重庆理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：近年来,随着光通信和无线传输通信的迅速发展,微波光子学成为当下的热门学科。与传统的电域相比,光域在微波信号产生和处理方面具有操作带宽大,高频,体积小,功耗低,抗电磁干扰等优势。因此,本文将侧重于研究利用光学方法产生微波信号和利用光学方法处理微波信号两个方面。在利用光学方法产生微波信号方面,本文首先对比分析了各种光学干涉仪的优缺点。由于光纤Sagnac干涉仪具有稳定性好,成本低,不易受温度影响等优势,因此选择光纤Sagnac干涉仪来产生梳状谱。然后,为了获得波长间距可调的梳状谱,在Sagnac干涉仪中插入了两段不同长度的保偏光纤(PMF),通过实验对比分析,发现在两段PMF的长度分别为11m和35m时,产生的梳状谱效果最好,其波长间距在0.132nm—0.212nm的范围内,都可以利用偏振控制器(PC)进行灵活调节。最后,利用一个光纤布拉格光栅(FBG)当作窄带滤波器,从梳状谱中滤出双波长,再通过光电探测器(PD)拍频得到微波信号,其频率可调范围为16.4 GHz—26.2 GHz,且信噪比(SNR)都大于30 dB。可见,本文提出的基于两段PMFs Sagnac干涉仪产生微波信号具有成本低,频率可调性好,操作灵活等特点,将会有广泛的应用价值。在利用光学方法处理微波信号方面,本文首先对比分析了各种电光调制器的优缺点。由于相位调制器(PM)具有成本低,系统简单,不易受零点漂移的影响等特点,所以选择了PM进行研究。将一根单模光纤(SMF)与PM构成双平行结构,把相位调制信号转化为强度调制信号(PM-IM)。然后,在SMF也插入参数相同的PM,并分别注入频率10G,20G为的射频信号(RF)和码率2 Gbit/s,2.5 Gbit/s的二进制序列,从而得到相移为π的相位编码微波信号。最后,把相移为π的相位编码微波信号的数据导入matlab中进行自相关函数的转化并进行对比分析,发现在RF信号的频率为20G,二进制序列的码率为2.5 Gbit/s,周期为6.4ns时,得到自相关函数的半高全宽(FWHM)为0.388ns,此时相位编码微波信号的脉冲压缩比最好,为16.5。可见,本文提出的基于双平行的相位调制器结构,处理得到的相位编码微波信号的脉冲压缩比高,且该结构易于集成,具有极大的商用价值。
[Abstract]:In recent years, with the rapid development of optical communication and wireless communication, microwave photonics has become a hot subject. Compared with the traditional electrical domain, optical domain has a large operating bandwidth in microwave signal generation and processing. High frequency, small size, low power consumption, anti-electromagnetic interference and other advantages. In this paper, we will focus on the generation of microwave signals by optical methods and the processing of microwave signals by optical methods, and the generation of microwave signals by optical methods. In this paper, the advantages and disadvantages of various optical interferometers are compared and analyzed. The optical fiber Sagnac interferometers have the advantages of good stability, low cost and not easy to be affected by temperature. Therefore, the optical fiber Sagnac interferometer is chosen to generate the comb spectrum. Then, in order to obtain the comb spectrum with adjustable wavelength spacing. Two different lengths of polarization maintaining fiber (PMF) have been inserted into the Sagnac interferometer. The experimental results show that the length of the two segments of PMF is 11m and 35m, respectively. The comb spectrum produced the best effect, its wavelength spacing in the range of 0.132nm-0.212nm, can be flexibly adjusted by using polarization controller PCS. Finally. A fiber Bragg grating (FBG) is used as a narrow band filter to filter out two wavelengths from the comb spectrum. The frequency adjustable range is 16.4 GHz-26.2 GHz, and the SNR is more than 30 dB. The microwave signal generated by the two-stage PMFs Sagnac interferometer is characterized by low cost, good frequency adjustment and flexible operation. There will be a wide range of applications. In the optical processing of microwave signals, the advantages and disadvantages of various electro-optic modulators are compared and analyzed in this paper. Because of the low cost and simple system of the phase modulator (PMM). It is not easy to be affected by 00:00 drift, so PM is chosen to be studied. A single mode fiber (SMFF) and PM are used to form a double parallel structure. The phase modulation signal is converted into the intensity modulation signal. Then, the same parameters are inserted into the SMF and the injection frequency is 10G. A 20 gigabyte radio frequency (RF) signal and a binary sequence with a bit rate of 2. 5 Gbit/s are obtained, and a phase coded microwave signal with phase shift to 蟺 is obtained. Finally, a phase coded microwave signal with phase shift to 蟺 is obtained. The data of phase coded microwave signal with phase shift to 蟺 are imported into matlab to transform the autocorrelation function and the frequency of RF signal is found to be 20G. When the binary sequence has a bit-rate of 2.5 Gbit / s and a period of 6.4 ns, the half-high full-width FWHM of the autocorrelation function is 0.388ns. At this point, the pulse compression ratio of phase coded microwave signal is the best, which is 16.5. it can be seen that the pulse compression ratio of the phase coded microwave signal is high based on the dual-parallel phase modulator structure proposed in this paper. The structure is easy to integrate and has great commercial value.
【学位授予单位】：重庆理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN925

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