【作者】 凌云；

【导师】 邱昆；

【作者基本信息】 电子科技大学 ， 光学工程， 2008， 博士

【摘要】 光分组交换结合了光信号处理速度快和分组交换统计复用率高的特点,是实现高速光传输无缝连接的最有效方式和全光网络的重要环节。光标签处理技术是光分组交换中的一项关键技术,是实现光分组交换的前提。本文采用理论分析,仿真计算和实验三种方法,围绕光标签处理技术进行新方法的探索和对已有方法进行改进。光副载波标签具有易于分离的特点,但是可传输的净荷速率受限于副载波频率。本文提出了一种标签信号采用非归零码(NRZ)调制,净荷信号采用双二进制载波抑制归零码(DCS-RZ)调制的光分组格式,既保持了标签和净荷的光功率谱分离的特点,又解除了对净荷信号速率的限制。该分组格式还具有很好的抗色散和非线性效应的特点,适合于长距离传输。论文通过理论分析和仿真对采用光滤波器对标签和净荷进行分离的对比度和误码率进行了研究,为优化光滤波器的设计提供了依据。在对残留旧标签对新标签干扰的研究中,发现新旧标签之间的同频干扰非常严重,因此提出了一种双频标签方案,很好地解决了新旧标签之间的干扰问题高速光码(OC)标签丌销小,但对光编解码器的要求高。本文提出了一种采用低速OC标签但不增加标签开销的相移键控光码(PSK-OC)标签和幅移键控(ASK)净荷正交调制光分组格式。通过仿真和理论分析对该分组格式存在的净荷对标签信号的干扰进行了研究,得到了通过增加光码的码长和增大净荷速率对标签码片速率的比值的方法来降低标签误码率的结论。OC标签具有可以在光域进行标签处理的优点,但是又存在擦除标签需要高速处理的要求。本文提出了一种将光码调制到光副载波上的方案,既保持了光码在光域处理的优点,又实现了采用光滤波器来分离标签的功能。对产生单边带光副载波和进行光功率的分配问题进行了理论分析和仿真验证,对采用光滤波器分离标签的可行性进行了仿真验证。OC标签的数目受限于可用码字的数目。为了增加OC标签的数目,本文提出了一种基于码字和时隙的二维光码(2D-OC)标签,极大地增加了标签数目。对2D-OC标签的标签误判概率进行了研究,找到了其与单个OC标签误码率的关系,并进行了相应的光分组交换实验研究。对净荷直接进行光码编码是一种隐式标签的表示方式。本文提出了这类分组交换的基于两级光开关的交换结构。修正了Gold序列的误码率计算中的问题,在增加偏振影响的情况下得到了新的Gold序列误码率计算公式。对影响多跳误码率的因素进行了研究,提出了将误码率和标签利用率作为节点权值的负载均衡算法。为了解决比特序列标签擦除难的问题,提出了一种将光码嵌入到比特序列标签的光分组中的方案,很好地解决了快速分离和插入标签的问题。为了解决输入光分组功率波动的问题,分别提出了采用基于半导体光放大器的马赫—曾德干涉仪(SOA-MZI)结构和法布里—珀罗半导体光放大器(FP-SOA)进行全光功率均衡的方案,通过理论分析和仿真计算验证了方案的可行性,并对影响光功率均衡性能的因素进行了分析。为了解决比特序列标签分离难的问题,提出了采用FP-SOA进行全光分离标签和净荷的方案,对其工作原理进行分析,对方案的可行性进行了仿真验证,得到了影响分离性能因素的关系。为了实现脉冲数目表示的生存时间处理中的脉冲数目减一的功能,提出了采用非平衡马赫—曾德干涉仪(AMZI)和FP-SOA的生存时间(TTL)处理方案,仿真计算验证了方案的可行性,得到了影响对比度的因素的关系。为了解决SOA和FP-SOA载流子恢复慢的问题,对量子点半导体光放大器(QD-SOA)的光信号处理进行了研究。建立了QD-SOA的分段模型,对基于量子点半导体光放大器的马赫—曾德干涉仪(QDSOA-MZI)结构的光硬限幅器和光功率均衡器进行了仿真研究。更多还原

【Abstract】 Optical packet switching(OPS), which combines the high-speed optical signal processing and the high multiplexing efficiency of the packet switching, is an effective method of connecting seamlessly the high bit-rate optical transmissions and an important part of all-optical networks. Optical label processing (OLP) is one of the key technologies in OPS and the premise of realizing OPS. This dissertation makes deep investigations into the OLP technology by searching new schemes and improving the existing methods. The methods including theoretical analysis, simulations and experiments are adopted in the dissertation.The scheme of optical subcarrier label has the advantage of easily separating the label and payload, but the bit-rate upper bound of the payload is limited by the subcarrier frequency. In this dissertation, a novel optical packet with non-return to zero (NRZ) label and duobinary carrier-suppressed return-to-zero (DCS-RZ) payload is proposed to solve the disadvantage of optical subcarrier label. The optical power spectra of the label and payload are divided as the same as the scheme of optical subcarrier label, but the bit-rate upper bound of the payload is disappearing. The proposed packet, which has very good characteristics of chromatic dispersion and nonlinearity tolerance, can be transmitted in the long-distance fiber. The contrast ratio and BER performances of using optical filter to separate the label and payload are studied in theory and in the simulation. The research results can benefit the optimal design of the optical filters. On the study of the interference between the residual labels and the new label, the BER performance is severely devastated by the interference. A double-frequency label scheme is proposed to solve the interference successfully.High chip-rate optical code (OC) label has short label length but makes it difficult to manufacture the encoder and decoder. A scheme which adopts low chip-rate but no extra label length is proposed in this dissertation. The OC label is phase-shift keying (PSK) modulated on the amplitude-shift keying (ASK) modulation payload. The label detection performance under the interference of the payload is studied in theory and in the simulation. The research results show that the label BER performance can be improved by increasing the code length or the bit-rate ratio of the payload to the label.The advantage of OC label is to recognize the label in optical domain and the disadvantage is the difficulty of erasing the label. In this dissertation, the OC label is proposed to be modulated on the optical subcarrier. The scheme not only maintains the all-optical label processing but also simply realizes the label extraction by using optical filter. The generation of single-band subcarrier and the optical power distribution on the optical carrier and subcarrier are studied in theory and in the simulation. The feasibility of separating the label and payload by using optical filter is proved by simulation.The number of OC label is limited by the amount of the available OCs. A code and time-slot two dimensional OC (2D-OC) label is proposed to expand the OC label number in this dissertation. The BER formula of 2D-OC label is obtained. The OPS experiment is performed by adopting the proposed 2D-OC label.The optical encoding directly on the payload is another OC label. A switching structure based on two-stage optical switch is proposed in the dissertation. The BER formula of Gold sequence is obtained by correcting the reported formula and taking the polarization into account. The multi-hops BER is studied based on the BER formula in the switching node. A load-balancing algorithm is proposed, which formulate the node weight with BER and the label utilization.For overcoming the problem of erasing the bit-serial label, an OC-embedding optical packet format is proposed in the dissertation. The scheme feasibility is proved by simulation.For removing the optical power fluctuation of the input optical packets, semiconductor optical amplifier and Mach-Zehnder interferometer (SOA-MZI) structure and Fabry-Perot semiconductor optical amplifier (FP-SOA) are separately proposed to performance optical power equalization in the dissertation. The working principle is described and the feasibility is proved in the simulation. The corresponding parameter effects are studied.For solving the problem of ail-optically separating the bit-serial label and the payload, the scheme based on FP-SOA is proposed in the dissertation. The working principle is introduced and the simulation is performed. The parameter effects are studied.For realizing to decrease one pulse from the time-to-live (TTL) pulses, a scheme based on asymmetrical Mach-Zehnder interferometer (AMZI) and FP-SOA is proposed in the dissertation. The scheme feasibility is proved by simulation.For dealing with the slow carrier recovery in SOA and FP-SOA, the optical signal processing researches is performed on quantum dots semiconductor optical amplifier (QD-SOA). The schemes of optical hard limiter and optical power equalizer based on QD-SOA are studied by using the sectional simulation model.更多还原