本文關鍵詞： 微波信號 Sagnac干涉儀 可調頻率 相位調制器 脈沖壓縮比　出處：《重慶理工大學》2017年碩士論文　論文類型：學位論文

【摘要】：近年來,隨著光通信和無線傳輸通信的迅速發(fā)展,微波光子學成為當下的熱門學科。與傳統(tǒng)的電域相比,光域在微波信號產生和處理方面具有操作帶寬大,高頻,體積小,功耗低,抗電磁干擾等優(yōu)勢。因此,本文將側重于研究利用光學方法產生微波信號和利用光學方法處理微波信號兩個方面。在利用光學方法產生微波信號方面,本文首先對比分析了各種光學干涉儀的優(yōu)缺點。由于光纖Sagnac干涉儀具有穩(wěn)定性好,成本低,不易受溫度影響等優(yōu)勢,因此選擇光纖Sagnac干涉儀來產生梳狀譜。然后,為了獲得波長間距可調的梳狀譜,在Sagnac干涉儀中插入了兩段不同長度的保偏光纖(PMF),通過實驗對比分析,發(fā)現在兩段PMF的長度分別為11m和35m時,產生的梳狀譜效果最好,其波長間距在0.132nm—0.212nm的范圍內,都可以利用偏振控制器(PC)進行靈活調節(jié)。最后,利用一個光纖布拉格光柵(FBG)當作窄帶濾波器,從梳狀譜中濾出雙波長,再通過光電探測器(PD)拍頻得到微波信號,其頻率可調范圍為16.4 GHz—26.2 GHz,且信噪比(SNR)都大于30 dB�？梢�,本文提出的基于兩段PMFs Sagnac干涉儀產生微波信號具有成本低,頻率可調性好,操作靈活等特點,將會有廣泛的應用價值。在利用光學方法處理微波信號方面,本文首先對比分析了各種電光調制器的優(yōu)缺點。由于相位調制器(PM)具有成本低,系統(tǒng)簡單,不易受零點漂移的影響等特點,所以選擇了PM進行研究。將一根單模光纖(SMF)與PM構成雙平行結構,把相位調制信號轉化為強度調制信號(PM-IM)。然后,在SMF也插入參數相同的PM,并分別注入頻率10G,20G為的射頻信號(RF)和碼率2 Gbit/s,2.5 Gbit/s的二進制序列,從而得到相移為π的相位編碼微波信號。最后,把相移為π的相位編碼微波信號的數據導入matlab中進行自相關函數的轉化并進行對比分析,發(fā)現在RF信號的頻率為20G,二進制序列的碼率為2.5 Gbit/s,周期為6.4ns時,得到自相關函數的半高全寬(FWHM)為0.388ns,此時相位編碼微波信號的脈沖壓縮比最好,為16.5。可見,本文提出的基于雙平行的相位調制器結構,處理得到的相位編碼微波信號的脈沖壓縮比高,且該結構易于集成,具有極大的商用價值。
[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.
【學位授予單位】：重慶理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN925

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