基于全光量化的光谱压缩方法研究

发布时间：2018-09-05 06:48

【摘要】：随着科学技术的不断发展,数字信号处理由于其自身的诸多优势,存在于我们生活的方方面面。在通信和军事上,数字信号处理技术彻底改变了旧时代的通信和雷达系统,使其高度数字化,大幅度提高了信号传输和处理能力。随着人们对数字信号处理提出更高的期望,也对模数转换器(ADC)的工作带宽和采样速率有了更高的要求。而传统的电子ADC由于其“电子瓶颈”的限制,无法满足高速高精度的模数转换器的要求,因此,光学ADC作为一种有效突破电子ADC瓶颈的方法,近年来得到广泛关注。本文重点是基于孤子自频移效应的全光量化,提出了一种新的光谱压缩方法——基于非线性光纤环镜(NOLM)结构的光谱压缩方法,以提高全光量化精度,并通过仿真及实验验证了此方法的可行性。论文主要内容如下:1.系统介绍了光学ADC的发展现状及其应用,对孤子自频移的的发现以及在全光量化中的发展做出了概述。2.通过麦克斯韦方程组推导并研究了适用于光脉冲在光纤中传输的广义非线性薛定谔方程,并探究了求解广义非线性薛定谔方程的数值方法——分步傅里叶法。介绍了脉冲在光纤中传输时所产生的一些非线性效应,并着重分析了孤子自频移的产生机理以及频移量的影响因素。3.根据NOLM的基本原理,提出了基于NOLM的光谱压缩方法,并且从数值分析和实验上进行了研究。数值仿真的结果表明:NOLM能够对无啁啾双曲正割脉冲进行光谱压缩,通过改变结构参数减小压缩后的光谱边带(或基座),以此结构参数对300fs的无啁啾双曲正割脉冲压缩,得到边带能量比为9.39%和谱宽为1.6nm的仿真结果。实验中,对NPR被动锁模光纤激光器产生的亚皮秒脉冲进行压缩,综合考虑边带能量比和压缩比,得到1.52nm的谱宽和6.53的压缩比。4.分别对色散渐增光纤(DIF)和反常色散高非线性光纤(HNLF)串联NOLM的二级光谱压缩进行了数值仿真研究。仿真结果表明,将NOLM连接于不同类型DIF之后,在孤子数N分别为0.5、1、1.4时,最大可以得到10.93的压缩比;将NOLM连接于反常色散高非线性光纤之后,当NOLM中为HNLF时,将压缩比从7.33提高到11.9。当NOLM中为色散位移光纤时,可以得到46.67的压缩比。
[Abstract]:With the development of science and technology, digital signal processing exists in all aspects of our life because of its many advantages. In communication and military, digital signal processing technology has completely changed the communication and radar system of the old era, made it highly digital, and greatly improved the ability of signal transmission and processing. With the higher expectation of digital signal processing, the bandwidth and sampling rate of ADC (ADC) are also higher. Traditional electronic ADC can not meet the requirements of high speed and high precision analog-to-digital converters because of its "electronic bottleneck". Therefore, optical ADC, as an effective method to break through the bottleneck of electronic ADC, has been paid more and more attention in recent years. This paper focuses on all-optical quantization based on soliton self-frequency shift effect. A new spectral compression method, which is based on the (NOLM) structure of nonlinear fiber loop mirror, is proposed to improve the precision of all-optical quantization. The feasibility of this method is verified by simulation and experiment. The main contents of the thesis are as follows: 1. The development and application of optical ADC are introduced systematically. The discovery of soliton self-frequency shift and its development in all-optical quantization are summarized. The generalized nonlinear Schrodinger equation, which is suitable for optical pulse propagation in optical fiber, is derived and studied by Maxwell equations. The numerical method of solving generalized nonlinear Schrodinger equation, the fractional Fourier method, is also discussed. Some nonlinear effects of pulse propagation in optical fiber are introduced. The mechanism of self-frequency shift of soliton and the influencing factors of frequency shift are analyzed. According to the basic principle of NOLM, the spectral compression method based on NOLM is proposed, and the numerical analysis and experimental study are carried out. The numerical simulation results show that: NOLM can compress the non-chirped hyperbolic cut pulse and reduce the compressed spectral sideband (or pedestal) by changing the structure parameters, so that the non-chirped hyperbolic cut pulse of 300fs can be compressed by this structure parameter. The simulation results show that the side band energy ratio is 9.39% and the spectrum width is 1.6nm. In the experiment, the sub-picosecond pulse produced by NPR passive mode-locked fiber laser is compressed. The spectrum width of 1.52nm and the compression ratio of 6.53 are obtained by considering the side band energy ratio and compression ratio. The second order spectral compression of dispersion-increasing fiber (DIF) and anomalous dispersion high nonlinear fiber (HNLF) series NOLM are studied numerically. The simulation results show that the maximum compression ratio of 10.93 can be obtained when the soliton number N is 0.5 ~ (11) ~ (1.4) when the NOLM is connected to different types of DIF, and when the NOLM is connected to the anomalous dispersion high nonlinear fiber, when the NOLM is HNLF, the maximum compression ratio can be obtained. Increase the compression ratio from 7. 33 to 11. 9. A compression ratio of 46.67 can be obtained when NOLM is a dispersion-shifted fiber.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN911.7

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