【作者】 赵晓凡；

【导师】 娄采云；

【作者基本信息】 清华大学 ， 电子科学与技术， 2010， 博士

【摘要】 光信号处理技术是未来高速大容量光网络中的关键技术。论文主要基于半导体光放大器(SOA)、延迟干涉仪(DI)和光调制器等器件,研究了全光波长转换、光调制格式转换和全光信号再生等光信号处理技术和光脉冲幅度均衡技术。论文建立了SOA和DI的数值模型并分析了SOA-DI光开关的工作原理。基于SOA的数值模型,研究了基于SOA结合光滤波器的光脉冲幅度均衡技术。在理论研究的基础上进行了实验验证,实现了幅度抖动大于40%的20 GHz光脉冲的幅度均衡,当光脉冲重复频率提高至40 GHz、幅度抖动大于30%时,仍可得到很好的均衡效果。基于SOA-DI光开关实现了10 Gb/s和40 Gb/s RZ信号波长转换。针对NRZ信号,提出了一种基于非线性偏振开关(NPS)结合DI的NRZ信号波长转换方案。利用DI的整形功能,有效改善了NPS波长转换信号的消光比和Q值,提高了波长转换信号背靠背和传输后的接收灵敏度。利用延时量可调的DI,实现了基于SOA-DI光开关的NRZ到RZ全光格式转换。该方案具有适用于不同速率、转换信号脉宽可调的优点,且当SOA工作在饱和状态时,该方案对时钟功率变化不敏感。提出了基于级联铌酸锂相位强度调制器和色散补偿光纤的NRZ到RZ格式转换器,获得了低占空比、低抖动的RZ信号,转换后的RZ信号具有良好的传输性能。论文最后部分研究了基于SOA-DI光开关的全光信号再生技术。通过理论和实验研究了基于SOA-DI光开关的全光2R再生,利用蓝移滤波技术抑制了40 Gb/s再生时的码型效应。提出了一种基于SOA-DI-SOA结构的新型全光2R再生器,利用另一SOA中的交叉增益调制效应实现了SOA-DI输出信号的再生放大。该方案有效地提高了SOA-DI 2R再生器的性能和对恶化信号的再生容限。实现了以SOA-DI作判决门、自脉动激光器作时钟提取单元的40 Gb/s全光3R再生,实现了PMD恶化信号的时钟提取和再生,消除了ASE恶化信号的误码平台,实现无误码操作。更多还原

【Abstract】 Optical signal processing is a key technology in future high-speed and large- capacity optical network. In this dissertation, optical signal processing technologies including all-optical wavelength conversion, optical format conversion and all-optical regeneration as well as optical pulse-amplitude-equalization technology are intensively studied based on optical devices such as semiconductor optical amplifier (SOA), delayed interferometer (DI) and optical modulators.Firstly, we present numerical models for SOA and DI, and analyze the operation principle of the SOA-DI optical gate. Based on the numerical model of SOA, a method of optical pulse-amplitude-equalization is proposed and theoretically studied. Experiments are also carried out to verify the proposed scheme. The experimental and numerical results agree well. Amplitude equalization of optical pulses with amplitude fluctuation of more than 40% at a repetition rate of 20 GHz is demonstrated. The scheme also works well when it is applied to the amplitude equalization of 40 GHz optical pulses with amplitude fluctuation of greater than 30%.All-optical wavelength conversion of RZ signals at 10 Gb/s and 40 Gb/s is demonstrated based on the SOA-DI optical gate. Wavelength converter based on a nonlinear polarization switch (NPS) and a DI is proposed and demonstrated for the wavelength conversion of NRZ signals. The extinction ratio and the Q-factor of the wavelength-converted signal based on NPS are effectively improved due to the reshaping function of the DI, leading to the receiver sensitivity improvement of the NPS-converted signal before and after transmission.By using a DI with variable delays, we demonstrate an all-optical NRZ-to-RZ format converter. The scheme can be used to convert input signals at different bit rates and can obtain converted signals with tunable duty cycles. The format converter is insensitive to the power fluctuation of the optical clock as the SOA works in the saturation regime. Besides, we also propose and demonstrate NRZ-to-RZ format conversion based on cascaded lithium niobate phase and intensity modulators followed by a section of DCF. By using this scheme, RZ signal with a low duty cycle and low timing jitter can be obtained. The converted RZ shows excellent transmission performance.Finally, all-optical regeneration based on SOA-DI configuration is investigated. The SOA-DI-based all-optical 2R regenerator is theoretically and experimentally studied. The blue-shifted optical filtering technique is used to mitigate the impact of pattern effects at a bit rate of 40 Gb/s. A novel all-optical 2R regenerator based on SOA-DI-SOA configuration is proposed and demonstrated. The cross-gain modulation in a second SOA is utilized to achieve the regenerative amplification of the optical signal out of DI. The performance of the SOA-DI regenerator is greatly improved and is more tolerant to the degradation of the input signal. Furthermore, 40 Gb/s 3R regeneration of degraded signals is also demonstrated by incorporating the SOA-DI as the optical decision gate and a self-pulsating laser as the clock recovery unit. The waveform of the PMD-degraded signal is successfully restored after the 3R regeneration. The bit-error rate floor of the ASE-degraded signal is removed and error-free operation is achieved.更多还原