基于外调制器的微波光子技术在微波与传感系统中的应用

发布时间：2018-06-20 03:05

本文选题：微波光子技术 + 外调制器　；参考：《南京大学》2016年博士论文

【摘要】：微波光子学是一门交叉学科,研究的主要问题是在光域里产生、处理和传输微波信号。微波光子学的应用领域包括光载无线通信系统、雷达系统、光信号处理、传感等领域。因为光学器件具有大带宽、重量轻、高可调性和重构性和抗电磁干扰等优点,微波光子技术被认为能够有效地克服“电子瓶颈“问题。本论文基于各种外调制器提出了几个微波光子系统解决了微波信号的产生、传输和处理上的一些问题。另外,本论文还将微波光子技术应用在了多纵模光纤激光器传感器上。本论文的主要工作如下：1.我们提出了一种基于DFB激光器的光学相位共轭变换器(OPC)用来补偿微波光子链路中的色散。DFB激光器提供了OPC中的泵浦光源同时自身也是可以引发四波混频(FWM)的介质。相比于基于半导体光放大器和色散位移光纤的OPC,我们提供了一个集成度更高的方案。实验结果显示,通过这种OPC,50.4 km的微波光子链路中的色散被补偿并且补偿带宽高达33 GHz,无杂散动态范围(SFDR)也提高了12.6dB·Hz2/3。在微波光子链路中的色散点9.2 GHz处,125 Mb/s幅移键控信号的传输性能也得到了提高。2.我们提出了一种基于光电振荡器(OEO)的全占空比三角波发生器。OEO的振荡频率决定了三角波脉冲的重复频率。通过将OEO中的马赫曾德调制器(MZM)偏置在正交点,OEO的小信号增益最大化同时产生的偶次谐波被抑制。通过精确控制OEO的小信号增益,使得基波的幅度是三次谐波幅度的9倍。在光电探测器(PD)产生的电信号经过一个90度移相器之后就能够产生三角波脉冲。实验中OEO的频率可以从2 GHz调谐到10 GHz,OEO的相位噪声在10 kHz处为-101.7 dBc/Hz。我们也测试了重复频率为3 GHz和6 GHz的三角波,它们与理想三角波的均方根误差分别为6.4927e-4和9.0932e-4。3.基于偏振调制器和双偏振调制器,我们提出了一种新型的微波频移键控(FSK)发生器。其中偏振调制器用来调制输入线偏振光的偏振态,使得输出光的偏振态在两个正交方向切换,也就是产生了偏振键控(PolSK)信号。双偏振调制器由偏振复用的两个子MZM组成。这两个子MZM被分别加上了频率不同的微波信号。偏振调制器产生的PolSK信号送入双偏振调制器,通过偏振控制器将PolSK的轴对准双偏振调制器的主轴,PolSK信号就能被转换成微波FSK信号。实验上我们将子MZM偏置在正交点并分别加上了3 GHz和6.5 GHz的信号,得到了载频为3/6.5 GHz比特率为1.25 Gb/s的FSK信号并且传输了10 km。另外我们还将MZM偏置在了最小传输点,得到了抑制载波的FSK信号。这种信号能够克服因光纤产生的微波功率衰减效应并且能够实现载频倍频。当加在MZM上的微波信号的频率是3/7 GHz时,我们得到了倍频的载频为6/14 GHz并且比特率为2.5 Gb/s的FSK信号。4.我们提出了一种有多个可调独立通带的微波光子滤波器(MPF)。使用的光源是自发辐射的宽谱光源并被一个耦合器分成N路。其中1路被送入相位调制器另外N-1路被光延时线延时。这N路分支被合路之后再送入色散补偿光纤然后在PD上进行光电转换。每一路延时的宽谱光与相位调制器产生的宽谱边带进行拍频就能产生出MPF的一个通带。通过调谐宽谱光的延时,通带的中心波长就能够得到调谐。在实验上我们演示了两个独立可调的通带,这两个通带能够独立地从DC调谐到30 GHz,通带3 dB带宽为250 MHz。我们也测试了MPF的稳定性。在1.5小时之内,当第一个通带的中心频率是8 GHz时,它的中心频率和强度的变化分别为31 MHz和0.4 dB；当第二个通带的中心频率在14 GHz时,它的中心频率和强度的变化分别为37 MHz和0.34 dB。另外我们还测试了MPF的SFDR。实验结果显示中心频率为1 GHz和4 GHz的通带的SFDR分别为73.5 dB·Hz2/3和73 dB-Hz2/3.5.我们对一种基于相移光纤光栅(PS-FBG)的单通带MPF进行了线性化。当一个相位调制的双边带(DSB)信号被送入PS-FBG时,如果一个边带落入PS-FBG反射带的透射缺口,从PS-FBG反射的信号就会转化成强度调制的单边带(SSB)信号,从而产生MPF的一个通带。通过调谐光载波的波长,通带的中心频率就能随之调谐。通过利用铌酸锂相位调制器中的双折射效应和偏振分集接收机,我们提高了这种MPF的SFDR。实验结果单通带MPF的通带宽度为80 MHz,调谐范围为5.5 GHz。SFDR被提高了13.1 dB。6.基于双平行马赫曾德调制器(DPMZM)和数字信号处理算法,我们提出并验证了一种具有高转换效率和高SFDR的微波光子混频器。射频信号和中频信号分别加在DPMZM里的两个平行的MZM上,使得射频和中频的隔离度趋近于无穷。当DPMZM的三个偏置都偏置在最小传输点时,光载波就能得到极大地抑制。因此对于PD来说,相同的输入光功率条件下能够产生更大的中频信号,因此转换效率就得到了提高。初步的实验显示转换效率最高能达到-12.7 dB。另一方面,我们提出一种简单的DSP算法提高了混频器的SFDR。这种算法不需要通常DSP算法所需要的系统的精确参数而只需要知道本振信号的调制深度。在实验上,通过该算法,混频器的SFDR从101.5dB·Hz2/3提高到了114.5 dB·Hz4/5。7.我们提出了一个多纵模光纤激光器传感器的复用方案。通过在光纤激光器谐振腔中插入两个匹配的波分复用器(WDM)和一个半导体光放大器,实现了激光器的多波长激射。对应于每一个WDM通道都产生了一个波长,并且由于WDM通道的带宽远大于纵模的自由谱程(FSR),因此每一个波长都含有多个纵模。我们在两个WDM之间的光纤上加上传感量。将激光器的多波长输出送入波分解复用器(DeWDM)将波长分开之后分别送入一个PD进行拍频解调就能解调出传感信号。一个初步的实验复用了一个应变传感器和一个温度传感器。
[Abstract]:Microwave photonics is a cross discipline. The main problem is to produce and transmit microwave signals in the optical domain. The applications of microwave photonics include optical wireless communication systems, radar systems, light signal processing, sensing and other fields. The optical devices have wide bandwidth, light weight, high tunability, reconfiguration and anti electromagnetic drying. The microwave photon technology is considered to be able to overcome the "electronic bottleneck" problem effectively. Based on various external modulators, several microwave photonic systems have been proposed to solve the problems of microwave signal generation, transmission and processing. In addition, the microwave photons are applied to the multi longitudinal mode fiber laser sensing in this paper. The main work of this paper is as follows: 1. we propose an optical phase conjugate converter based on DFB laser (OPC) to compensate for the dispersion.DFB laser in the microwave photonic link to provide the pump source in the OPC and the medium that can also cause the four wave mixing (FWM), compared to the semiconductor optical amplifier and the optical amplifier. The OPC of the dispersion shifted fiber provides a more integrated scheme. The experimental results show that the dispersion in the 50.4 km microwave photonic link is compensated and the compensation bandwidth is up to 33 GHz through this OPC, and the non stray dynamic range (SFDR) also improves the 12.6dB Hz2/3. dispersion point 9.2 GHz, 125 Mb/s amplitude in the microwave photonic link. The transmission performance of the shift keying signal has also been improved by.2.. We propose a total duty ratio triangular wave generator based on the optoelectronic oscillator (OEO), which determines the repetition frequency of the triangular wave pulse. By offset the Maher Ceng De modulator (MZM) in the OEO at the positive point, the small signal gain of the OEO is maximized simultaneously. The even subharmonic is suppressed. The amplitude of the base wave is 9 times the amplitude of the three harmonic by precisely controlling the small signal gain of the OEO. The electrical signal generated by the photodetector (PD) can produce a triangular wave pulse after a 90 degree phase shifter. In the experiment, the frequency of the OEO can be tuned from 2 GHz to 10 GHz, and the phase noise of OEO is at 10 kHz. -101.7 dBc/Hz. we also tested the trigonometric waves with repeated frequencies of 3 GHz and 6 GHz, and their root mean square errors with ideal triangular waves are 6.4927e-4 and 9.0932e-4.3. based on polarization modulator and dual polarization modulator. We propose a new type of microwave frequency shift keying (FSK) generator, in which the polarization modulator is used to modulate the input line bias. The polarization state of the light makes the polarization state of the output light switch in two orthogonal directions, that is, the polarization keying (PolSK) signal is produced. The dual polarization modulator consists of two sub MZM of polarization multiplexing. The two sub MZM are separately added to the different frequency microwave signals. The PolSK signals produced by the polarizer are sent to the dual polarization modulator. The over polarization controller aligns the axis of PolSK with the spindle of the dual polarization modulator, and the PolSK signal can be converted into a microwave FSK signal. In the experiment we offset the sub MZM at the positive point and add 3 GHz and 6.5 GHz signals respectively, and the FSK signal with a 3/6.5 GHz bit rate of 1.25 Gb/s is obtained and the 10 km. is transmitted. In addition, we will also MZM the MZM. It is biased at the minimum transmission point and gets the FSK signal to suppress the carrier. This signal can overcome the microwave power attenuation effect caused by the fiber and can achieve carrier frequency doubling. When the frequency of the microwave signal added to the MZM is 3/7 GHz, we get the FSK signal.4. with a frequency multiplier of 6/14 GHz and a bit rate of 2.5 Gb/s. We have proposed a microwave photon filter (MPF) with multiple adjustable independent passbands. The light source used is a broad spectrum source of spontaneous radiation and is divided into a N path by a coupler. 1 of them are sent into the phase modulator and the N-1 road is delayed by the optical delay line. The branch of the N road is then sent to the dispersion compensated fiber and then on the PD. Electrical conversion. A wide spectral band of wide spectral light generated by each time delay and a phase modulator produced by the phase modulator can produce a passband of the MPF. By tuning the delay of the broad spectrum light, the central wavelength of the passband can be tuned. In the experiment we demonstrate two independent tunable passbands, which can be tuned from DC to 30 G independently. Hz, with a band 3 dB bandwidth of 250 MHz., we also tested the stability of MPF. Within 1.5 hours, when the central frequency of the first pass is 8 GHz, its central frequency and strength changes are 31 MHz and 0.4 dB, respectively, when the central frequency of the second passband is 14 GHz, the changes in the center frequency and intensity are 37 MHz and 0.34 dB. respectively. In addition, we also tested the SFDR. experimental results of MPF showing that the SFDR of a passband with a center frequency of 1 GHz and 4 GHz is 73.5 dB. Hz2/3 and 73 dB-Hz2/3.5., respectively. We linearize a single pass band MPF based on phase shift fiber Bragg grating (PS-FBG). Falling into the transmission gap of the PS-FBG reflector, the signal reflected from the PS-FBG will be converted into a intensity modulated single band (SSB) signal, thus producing a passband of the MPF. By tuning the wavelength of the optical carrier, the central frequency of the passband can be tuned accordingly. By using the birefringence effect and polarization diversity receiver in the lithium niobate phase regulator, I We improved the MPF's SFDR. experiment results with the band width of 80 MHz, and the tuning range of 5.5 GHz.SFDR was improved by 13.1 dB.6. based on the dual parallel Maher Ceng De modulator (DPMZM) and digital signal processing algorithm. We proposed and verified a microwave photonic mixer with high conversion efficiency and high SFDR. If the intermediate frequency signals are added to the two parallel MZM in the DPMZM, the isolation of the radio frequency and intermediate frequency is close to infinity. When the three biases of the DPMZM are biased at the minimum transmission point, the optical carrier can be greatly suppressed. Therefore, for the PD, the same input light power can produce a larger intermediate frequency signal, thus conversion. Efficiency is improved. Preliminary experiments show that the maximum conversion efficiency can reach -12.7 dB. on the other hand, we propose a simple DSP algorithm to improve the mixer's SFDR., which does not require the exact parameters of the system required by the usual DSP algorithm but only needs to know the modulation depth of the signal signal. The method, the SFDR of the mixer is improved from 101.5dB to Hz2/3 to 114.5 dB. Hz4/5.7.. We put forward a multiplexing scheme of multi longitudinal mode fiber laser sensor. By inserting two matched wave division multiplexers (WDM) and a semiconductor optical amplifier in the resonator of the fiber laser, the laser multi wavelength lasing is realized. Each WDM channel produces a wavelength, and because the bandwidth of the WDM channel is much larger than the free spectrum of the longitudinal mode (FSR), each wavelength contains multiple longitudinal modes. We add the sense of upload to the fiber between two WDM. The multiwavelength output of the laser is sent to the wave decomposition reagent (DeWDM) and the wavelength is separated into a P respectively. D can demodulate the sensing signal by beat frequency demodulation. A preliminary experiment multiplexed a strain sensor and a temperature sensor.
【学位授予单位】：南京大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN015

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