高速相干光通信系統(tǒng)中關(guān)鍵技術(shù)的研究
發(fā)布時間：2018-08-13 20:54
【摘要】：近些年,隨著信息業(yè)務(wù)容量持續(xù)增長,進(jìn)而通信系統(tǒng)的容量需求也不斷提高。100G規(guī)模商用的進(jìn)程已經(jīng)開始。隨著模數(shù)轉(zhuǎn)換(ADC)、數(shù)字信號處理(DSP)、光器件制造等技術(shù)的發(fā)展,相干光通信重新成為研究熱點。數(shù)字相干光通信是100G技術(shù)的重要支撐,也是未來光通信的必然發(fā)展道路。通過結(jié)合相干檢測和DSP技術(shù),數(shù)字相干光通信可將載波相位恢復(fù)、偏振跟蹤等工作在電域中實現(xiàn),突破了傳統(tǒng)模擬相干光通信的障礙。 相干光通信系統(tǒng)中,光源、發(fā)送端和接收端是三個重要組成部分。對于光源,要求光譜線寬窄、頻率穩(wěn)定度高,當(dāng)前器件技術(shù)已經(jīng)很好地達(dá)到該要求,但如何測量窄線寬激光器的線寬并使測量系統(tǒng)集成化是有待解決的問題。對于發(fā)送端,可通過外調(diào)制技術(shù)完成調(diào)制工作,廣泛使用基于馬赫-曾德爾調(diào)制器(MZM)的IQ調(diào)制器來實現(xiàn)高階調(diào)制格式,但MZM在使用過程中需要穩(wěn)定控制偏置點以保持良好的調(diào)制效果。對于接收端,可采用平衡接收技術(shù)、DSP技術(shù)等完成解調(diào)、補償傳輸損傷等功能。此外,前向糾錯編碼(FEC)技術(shù)可以很好地抑制信道損傷,因此已被廣泛應(yīng)用在相干光通信系統(tǒng)中,相應(yīng)的需要高速可靠的編譯碼器,在接收端有譯碼器。光源、發(fā)送端、接收端這三部分有各自需要達(dá)到的要求及瓶頸問題,因此每一項解決問題的關(guān)鍵技術(shù)都具有重要的研究意義。 本論文圍繞高速相干光通信系統(tǒng)中的關(guān)鍵技術(shù),特別是高速相干光通信系統(tǒng)中發(fā)射端的關(guān)鍵技術(shù)開展了深入系統(tǒng)的理論和實驗研究。本論文的主要創(chuàng)新點和研究成果包括： 1.提出并實現(xiàn)了改進(jìn)的延時自外差窄線寬半導(dǎo)體激光器線寬測量系統(tǒng)。該測量系統(tǒng)以單激光器延時自外差法為基礎(chǔ),通過引入光學(xué)環(huán)形器和法拉第旋轉(zhuǎn)反射鏡,使得測量所需的延時光纖長度減半,有效地減小了系統(tǒng)所占體積,提高了系統(tǒng)集成度。利用該測量系統(tǒng)成功地對500kHz線寬的半導(dǎo)體激光器進(jìn)行了測量。該測量系統(tǒng)適用于測量線寬大于20kHz的半導(dǎo)體激光器,調(diào)整系統(tǒng)中延時光纖長度可測量線寬更窄的半導(dǎo)體激光器。 2.提出了一種新型的適用于鈮酸鋰MZM的偏置點穩(wěn)定控制技術(shù)。該技術(shù)中通過監(jiān)測MZM輸出光信號的平均光功率對偏置點漂移進(jìn)行初步判斷,再根據(jù)MZM輸出光信號平均光功率的一階與二階導(dǎo)數(shù)之間的比值確定漂移的真實性,在漂移確實發(fā)生后判斷出漂移方向,進(jìn)而可以相應(yīng)地調(diào)整偏置電壓,達(dá)到對MZM偏置點穩(wěn)定控制的目的。理論研究表明,該技術(shù)可以將MZM的偏置點穩(wěn)定控制在傳輸響應(yīng)曲線上任一位置,可適用于多種調(diào)制格式,與調(diào)制速率無關(guān)。 3.基于所提出的新型MZM偏置點穩(wěn)定控制技術(shù),實現(xiàn)了MZM偏置點穩(wěn)定控制反饋系統(tǒng)。搭建了實驗測試系統(tǒng),通過測試對反饋系統(tǒng)進(jìn)行了功能驗證和性能評估。實驗測試結(jié)果表明,利用所提出的新型技術(shù),能夠正確地實現(xiàn)對MZM的偏置點進(jìn)行穩(wěn)定控制,偏置點可為傳輸響應(yīng)曲線上任一位置,并且MZM輸出光信號平均光功率的波動被控制在±4%之內(nèi)。在調(diào)制速率為10Gbit/s,調(diào)制格式為非歸零開關(guān)鍵控(NRZ-OOK)的背靠背系統(tǒng)測試中,若不包含偏置點穩(wěn)定控制反饋系統(tǒng),誤碼率會從10-9級別惡化到10-2級別,而包含偏置點穩(wěn)定控制反饋系統(tǒng)后,誤碼率可以保持在10-9級別,很好地保持了系統(tǒng)性能。 4.理論分析了差分相位監(jiān)測器的工作原理,結(jié)果表明差分相位監(jiān)測器可用于對調(diào)制光信號進(jìn)行實時相位監(jiān)測,且適用于各種進(jìn)行相位調(diào)制的調(diào)制格式。基于差分相位監(jiān)測器,提出了適用于IQ調(diào)制器的基于相位監(jiān)測的偏置點穩(wěn)定控制技術(shù)。理論研究表明,偏置點漂移現(xiàn)象會影響調(diào)制光信號的相位,利用差分相位監(jiān)測器來進(jìn)行實時相位監(jiān)測,便可根據(jù)相位誤差來分析偏置點漂移程度,進(jìn)而可以通過反饋系統(tǒng)對IQ調(diào)制器的偏置點進(jìn)行穩(wěn)定控制。 5.設(shè)計了集成IQ發(fā)射機。集成IQ發(fā)射機采用了一體化解決方案,使調(diào)制與控制有效結(jié)合,硬件與軟件有效集成。在實現(xiàn)方案中,硬件部分集成了調(diào)制與控制需要的各器件、模塊、電路,并進(jìn)行了模塊化的設(shè)計,重點設(shè)計了增益控制模塊、偏置控制模塊和控制處理單元等部分；軟件部分研發(fā)了配套的上層控制軟件,可設(shè)置控制參量并監(jiān)控集成IQ發(fā)射機的工作狀態(tài)。該集成IQ發(fā)射機采用外調(diào)制方式,支持高階調(diào)制格式,調(diào)制速率最高可達(dá)22.5GBaud,并擁有豐富的、友好的、便捷的人機操控接口,具備自動進(jìn)行偏置點穩(wěn)定控制的功能。 6.獨立完成了集成IQ發(fā)射機樣機的研制工作,包括硬件設(shè)計與調(diào)試,軟件編寫等。搭建了實驗測試平臺,利用信號分析儀和基于數(shù)字相干技術(shù)的光調(diào)制信號分析儀,對樣機進(jìn)行了時域測試,驗證了其功能并評估了其性能。測試時的調(diào)制格式為QPSK,并利用光調(diào)制信號分析儀得到了背靠背系統(tǒng)的指標(biāo)。當(dāng)調(diào)制速率為10GBaud時,測試結(jié)果顯示,該樣機正確地調(diào)制出了10GBaud的QPSK信號,EVM為9%,背靠背系統(tǒng)無誤碼。當(dāng)調(diào)制速率提高到22.5GBaud時,測試結(jié)果顯示,該樣機則正確地調(diào)制出了22.5GBaud的QPSK信號,EVM為1l%,背靠背系統(tǒng)也無誤碼。測試結(jié)果還顯示,樣機的信號損傷較小。 7.提出并驗證了一種簡單有效的四環(huán)搜索算法,可計算π旋轉(zhuǎn)低密度奇偶校驗(LDPC)碼校驗矩陣中四環(huán)(Girth-4)的個數(shù)。利用該算法,經(jīng)過分析比較,給出了幾組索引(Key),使得利用這幾組索引構(gòu)造的π旋轉(zhuǎn)LDPC碼,其校驗矩陣中不會存在四環(huán),進(jìn)而提升該π旋轉(zhuǎn)LDPC碼的性能。此外,基于對π旋轉(zhuǎn)LDPC碼編碼器硬件實現(xiàn)方式的研究分析,在硬件上實現(xiàn)了π旋轉(zhuǎn)LDPC碼編碼器。測試結(jié)果顯示,該硬件編碼器正確地完成了π旋轉(zhuǎn)LDPC碼編碼功能。 8.研究分析了LDPC碼的譯碼算法,利用DSP芯片實現(xiàn)了基于硬判決的BF算法譯碼器和基于軟判決的LLR BP算法譯碼器,并比較了兩種譯碼器的性能。測試結(jié)果表明,LLR BP算法譯碼器性能優(yōu)于BF算法譯碼器,該結(jié)論與理論分析結(jié)果一致。
[Abstract]:In recent years, with the continuous growth of information service capacity, the capacity requirement of communication system is also increasing. 100G commercial process has begun. With the development of analog-to-digital conversion (ADC), digital signal processing (DSP), optical device manufacturing and other technologies, coherent optical communication has become a research hotspot again. Digital coherent optical communication is an important 100G technology. By combining coherent detection with DSP technology, digital coherent optical communication can realize carrier phase recovery and polarization tracking in the domain, breaking through the obstacles of traditional analog coherent optical communication.
In coherent optical communication system, light source, transmitter and receiver are three important components. For light source, narrow spectral linewidth and high frequency stability are required. Current device technology has achieved this requirement very well, but how to measure the linewidth of narrow linewidth laser and integrate the measurement system is a problem to be solved. External modulation technology is used to complete the modulation work, and IQ modulator based on Mach-Zehnder modulator (MZM) is widely used to achieve high-order modulation format. However, MZM needs to stabilize the bias point to maintain good modulation effect. For the receiver, balanced reception technology, DSP technology can be used to complete demodulation to compensate transmission damage. In addition, forward error correction coding (FEC) technology can effectively suppress channel damage, so it has been widely used in coherent optical communication systems, the corresponding need for high-speed and reliable encoder and decoder at the receiver, light source, transmitter, receiver these three parts have their own needs and bottlenecks, so each of them has its own requirements and bottlenecks. The key technologies to solve problems have important research significance.
In this paper, the key technologies of high-speed coherent optical communication system, especially the key technologies of transmitter in high-speed coherent optical communication system, have been studied systematically and theoretically.
1. An improved delay self-heterodyne narrow linewidth semiconductor laser linewidth measurement system is proposed and implemented. The system is based on the single laser delay self-heterodyne method. By introducing an optical ring and a Faraday rotating mirror, the required delay fiber length is reduced by half, the volume of the system is reduced effectively, and the system is improved. A 500 kHz linewidth semiconductor laser has been successfully measured with this measuring system. The measuring system is suitable for measuring semiconductor lasers with linewidth greater than 20 kHz and adjusting the length of the delay fiber in the system to measure narrower linewidth.
2. A novel offset point stabilization control technique for lithium niobate MZM is proposed. The offset point drift is estimated by monitoring the average optical power of the MZM output signal, and then the drift is determined by the ratio of the first-order to the second-order derivative of the average optical power of the MZM output signal. After birth, the drift direction can be judged, and then the bias voltage can be adjusted accordingly to achieve the purpose of stabilizing the MZM bias point. Theoretical studies show that this technique can stably control the MZM bias point at any position on the transmission response curve, and can be applied to a variety of modulation formats, independent of modulation rate.
3. Based on the proposed new MZM bias stabilization control technology, the MZM bias stabilization control feedback system is realized. An experimental test system is built, and the feedback system is verified and evaluated by testing. The experimental results show that the proposed new technology can correctly stabilize the bias of MZM. With fixed control, the offset point can be any position on the transmission response curve, and the fluctuation of the average optical power of the MZM output signal is controlled within (+) 4%. At the modulation rate of 10 Gbit/s and the modulation format of NRZ-OOOK back-to-back system test, the bit error rate will be from 10-9 level if the offset point stabilization control feedback system is not included. Don't deteriorate to 10-2 level, but the BER can be maintained at 10-9 level with the bias stabilization control feedback system, and the system performance is well maintained.
4. The working principle of the differential phase monitor is analyzed theoretically. The results show that the differential phase monitor can be used for real-time phase monitoring of modulated optical signals and can be used for various modulation formats. Based on the differential phase monitor, a phase-based bias stabilization control technique for IQ modulator is proposed. Theoretical research shows that the phase of modulated optical signal is affected by the offset drift. The phase error can be used to analyze the offset drift, and then the offset of IQ modulator can be stably controlled by the feedback system.
5. The integrated IQ transmitter is designed. The integrated IQ transmitter adopts an integrated solution, which effectively combines modulation and control, and effectively integrates hardware and software. In the implementation scheme, the hardware part integrates all the components, modules and circuits needed for modulation and control, and carries out modular design. The gain control module and bias control module are designed in particular. The control module and the control processing unit, etc. The software part develops the matching upper control software, which can set the control parameters and monitor the working state of the integrated IQ transmitter. The control interface has the function of automatic bias point stability control.
6. The prototype of the integrated IQ transmitter has been developed independently, including hardware design and debugging, software compilation, etc. The experimental test platform has been set up. The time domain test of the prototype has been carried out by using signal analyzer and optical modulation signal analyzer based on digital coherence technology. The function of the prototype has been verified and its performance has been evaluated. When the modulation rate is 10 GBaud, the test results show that the prototype correctly modulates the QPSK signal of 10 GBaud, EVM is 9%, and the back-to-back system has no error code. When the modulation rate is increased to 22.5 GBaud, the test results show that the prototype correctly modulates 22 GBaud. 5 GBaud QPSK signal, EVM is 1l%, back-to-back system is also error-free. The test results also show that the signal damage of the prototype is small.
7. A simple and effective four-loop search algorithm is proposed and verified to calculate the number of Girth-4 rings in the check matrix of pion-rotating low-density parity-check (LDPC) codes. Furthermore, based on the research and analysis of the hardware implementation of the pion-rotating LDPC coder, the pion-rotating LDPC coder is implemented on the hardware. The test results show that the hardware encoder performs the function of the pion-rotating LDPC coder correctly.
8. The decoding algorithm of LDPC is studied and analyzed. The hard-decision-based BF algorithm decoder and the soft-decision-based LR BP algorithm decoder are implemented with DSP chip. The performance of the two decoders is compared. The test results show that the performance of the LLR BP algorithm decoder is better than that of the BF algorithm decoder.
【學(xué)位授予單位】：北京郵電大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TN929.1
本文編號：2182159
[Abstract]:In recent years, with the continuous growth of information service capacity, the capacity requirement of communication system is also increasing. 100G commercial process has begun. With the development of analog-to-digital conversion (ADC), digital signal processing (DSP), optical device manufacturing and other technologies, coherent optical communication has become a research hotspot again. Digital coherent optical communication is an important 100G technology. By combining coherent detection with DSP technology, digital coherent optical communication can realize carrier phase recovery and polarization tracking in the domain, breaking through the obstacles of traditional analog coherent optical communication.
In coherent optical communication system, light source, transmitter and receiver are three important components. For light source, narrow spectral linewidth and high frequency stability are required. Current device technology has achieved this requirement very well, but how to measure the linewidth of narrow linewidth laser and integrate the measurement system is a problem to be solved. External modulation technology is used to complete the modulation work, and IQ modulator based on Mach-Zehnder modulator (MZM) is widely used to achieve high-order modulation format. However, MZM needs to stabilize the bias point to maintain good modulation effect. For the receiver, balanced reception technology, DSP technology can be used to complete demodulation to compensate transmission damage. In addition, forward error correction coding (FEC) technology can effectively suppress channel damage, so it has been widely used in coherent optical communication systems, the corresponding need for high-speed and reliable encoder and decoder at the receiver, light source, transmitter, receiver these three parts have their own needs and bottlenecks, so each of them has its own requirements and bottlenecks. The key technologies to solve problems have important research significance.
In this paper, the key technologies of high-speed coherent optical communication system, especially the key technologies of transmitter in high-speed coherent optical communication system, have been studied systematically and theoretically.
1. An improved delay self-heterodyne narrow linewidth semiconductor laser linewidth measurement system is proposed and implemented. The system is based on the single laser delay self-heterodyne method. By introducing an optical ring and a Faraday rotating mirror, the required delay fiber length is reduced by half, the volume of the system is reduced effectively, and the system is improved. A 500 kHz linewidth semiconductor laser has been successfully measured with this measuring system. The measuring system is suitable for measuring semiconductor lasers with linewidth greater than 20 kHz and adjusting the length of the delay fiber in the system to measure narrower linewidth.
2. A novel offset point stabilization control technique for lithium niobate MZM is proposed. The offset point drift is estimated by monitoring the average optical power of the MZM output signal, and then the drift is determined by the ratio of the first-order to the second-order derivative of the average optical power of the MZM output signal. After birth, the drift direction can be judged, and then the bias voltage can be adjusted accordingly to achieve the purpose of stabilizing the MZM bias point. Theoretical studies show that this technique can stably control the MZM bias point at any position on the transmission response curve, and can be applied to a variety of modulation formats, independent of modulation rate.
3. Based on the proposed new MZM bias stabilization control technology, the MZM bias stabilization control feedback system is realized. An experimental test system is built, and the feedback system is verified and evaluated by testing. The experimental results show that the proposed new technology can correctly stabilize the bias of MZM. With fixed control, the offset point can be any position on the transmission response curve, and the fluctuation of the average optical power of the MZM output signal is controlled within (+) 4%. At the modulation rate of 10 Gbit/s and the modulation format of NRZ-OOOK back-to-back system test, the bit error rate will be from 10-9 level if the offset point stabilization control feedback system is not included. Don't deteriorate to 10-2 level, but the BER can be maintained at 10-9 level with the bias stabilization control feedback system, and the system performance is well maintained.
4. The working principle of the differential phase monitor is analyzed theoretically. The results show that the differential phase monitor can be used for real-time phase monitoring of modulated optical signals and can be used for various modulation formats. Based on the differential phase monitor, a phase-based bias stabilization control technique for IQ modulator is proposed. Theoretical research shows that the phase of modulated optical signal is affected by the offset drift. The phase error can be used to analyze the offset drift, and then the offset of IQ modulator can be stably controlled by the feedback system.
5. The integrated IQ transmitter is designed. The integrated IQ transmitter adopts an integrated solution, which effectively combines modulation and control, and effectively integrates hardware and software. In the implementation scheme, the hardware part integrates all the components, modules and circuits needed for modulation and control, and carries out modular design. The gain control module and bias control module are designed in particular. The control module and the control processing unit, etc. The software part develops the matching upper control software, which can set the control parameters and monitor the working state of the integrated IQ transmitter. The control interface has the function of automatic bias point stability control.
6. The prototype of the integrated IQ transmitter has been developed independently, including hardware design and debugging, software compilation, etc. The experimental test platform has been set up. The time domain test of the prototype has been carried out by using signal analyzer and optical modulation signal analyzer based on digital coherence technology. The function of the prototype has been verified and its performance has been evaluated. When the modulation rate is 10 GBaud, the test results show that the prototype correctly modulates the QPSK signal of 10 GBaud, EVM is 9%, and the back-to-back system has no error code. When the modulation rate is increased to 22.5 GBaud, the test results show that the prototype correctly modulates 22 GBaud. 5 GBaud QPSK signal, EVM is 1l%, back-to-back system is also error-free. The test results also show that the signal damage of the prototype is small.
7. A simple and effective four-loop search algorithm is proposed and verified to calculate the number of Girth-4 rings in the check matrix of pion-rotating low-density parity-check (LDPC) codes. Furthermore, based on the research and analysis of the hardware implementation of the pion-rotating LDPC coder, the pion-rotating LDPC coder is implemented on the hardware. The test results show that the hardware encoder performs the function of the pion-rotating LDPC coder correctly.
8. The decoding algorithm of LDPC is studied and analyzed. The hard-decision-based BF algorithm decoder and the soft-decision-based LR BP algorithm decoder are implemented with DSP chip. The performance of the two decoders is compared. The test results show that the performance of the LLR BP algorithm decoder is better than that of the BF algorithm decoder.
【學(xué)位授予單位】：北京郵電大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TN929.1
【相似文獻(xiàn)】
相關(guān)期刊論文 前10條
1 徐東明;相干光通信的實用化研究[J];現(xiàn)代有線傳輸;1996年02期
2 幺周石,胡渝;星間相干光通信技術(shù)的發(fā)展歷程與趨勢[J];光通信技術(shù);2005年08期
3 王玲;馮瑩;;衛(wèi)星相干光通信的研究進(jìn)展及趨勢[J];激光與光電子學(xué)進(jìn)展;2007年06期
4 胡毅;楊家龍;;40/100G相干光通信模塊的技術(shù)分析[J];烽火科技;2011年06期
5 牛麗紅;孔麗萍;;淺談相干光通信[J];中小企業(yè)管理與科技(下旬刊);2012年07期
6 謝福珍;相干光通信的最新成果簡介[J];光通信技術(shù);1986年02期
7 楊同友 ,李先源;相干光通信[J];電信科學(xué);1988年05期
8 段曉明;;外差相干光通信的現(xiàn)狀與發(fā)展方向[J];光纖與電纜及其應(yīng)用技術(shù);1990年01期
9 邊一;;相干光通信[J];光纖與電纜及其應(yīng)用技術(shù);1991年02期
10 姚建國;;相干光通信系統(tǒng)中的偏振控制技術(shù)[J];光通信技術(shù);1992年01期
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10 王麗枝;相干光通信外差探測技術(shù)研究[D];西安電子科技大學(xué);2011年
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