【作者】 唐伟；

【导师】 张静；

【作者基本信息】 电子科技大学 ， 工程硕士（专业学位）， 2019， 硕士

【摘要】 大数据、人工智能、超高清视频的发展将进一步促使通信传输速率的提升。传统的电信号处理速度已经远远小于通信传输速率,用光信号处理代替电信号处理,已经成了突破通信系统瓶颈的趋势。空间光学中通过使用光学透镜就可以实现空间傅里叶变换以及全息影像等复杂功能,随着时空对偶原理的提出,空间光学中的信号处理技术逐渐被应用于时域光信号处理,催生出了时间透镜。与空间透镜一样,时间透镜也具有系统元件少、功能强大的特点,是极具潜力的光信号处理方案。本文基于时空对偶原理,类比于空间透镜中聚焦高斯光束在衍射极限下形成艾里斑,推导出时域分辨率的计算公式以及品质因数两大参数,并以此为标准分析了常见的时间透镜。普通的基于电光相位调制的线性时间透镜性能有限,而基于非线性效应的实现方法系统过于复杂,还存在系统不稳定等问题,因而本文提出了调制线性扫频信号实现新型时间透镜的方法,利用高速任意波形发生器直接产生两路正交的线性扫频信号,并通过I/Q调制方式调制到光波上,相比于传统电光相位调制的时间透镜,能够使时域孔径和品质因数实现数量级的提升。在此基础上研究了相位调制器、马赫-增德尔调制器以及I/Q调制器的调制原理,从实验精度出发,利用I/Q调制器进行了线性扫频信号调制实验,时域孔径达到了4.4 ns,品质因数达到558,远远大于传统时间透镜。此外还研究了两种方法用于扩展线性扫频时间透镜带宽。本文还针对时间透镜在光信号处理方面的应用,构建了基于线性扫频时间透镜的光脉冲整形仿真系统。在时域成像方面,探究了时间透镜对于脉宽为1 ps高斯脉冲的缩放因子范围,结合了I/Q调制器的调制过程,研究了各种系统因素对时域成像的影响,仿真结果表明高阶相位项和失焦是产生时域像差的主要原因;时域傅里叶变换方面,对时间透镜的傅里叶变换过程进行了仿真分析,基于色散系统中脉冲频谱传输的不变性以及高斯脉冲时域波形和频谱包络的对应性,实现了基于频域到时域转换的高斯脉冲无失真传输系统。更多还原

【Abstract】 The development of big data,AI and ultra-high definition video will accelerate the speed of communication transmission.The traditional electrical processing speed is far less than the speed of communication transmission.Applying optical signal processing instead of electrical signal processing has become a trend to break through the bottleneck of communication system.In spatial optics,complex functions such as spatial Fourier transformation and holographic image can be realized by optical lenses.As the principle of space-time duality develops,signal processing technology in spatial optics is gradually applied to time-domain,namely,time lens.Like the spatial lens,time lens also has the characteristics of less system components and powerful functions,which has great potential in optical signal processing.Based on the principle of space-time duality and analogy with the concept of Airy disk in spatial lens,this thesis deduces the calculation formula of time-domain resolution and the figure of merit,and then analyses the common ways to realize time lens.The performance of traditional linear time lens based on electro-optical phase modulation is limited,and the method based on nonlinear process is too complicated and also has instable problem.Therefore,this thesis proposes a method that directly generates quadratic phase and then realizes the time lens through modulation.Two orthogonal linear sweep signals are directly generated by high-speed arbitrary waveform generator and modulated by I/Q modulator.Compared with the traditional electro-optical phase modulation time lens,the time aperture and figure of merit can be increased by orders of magnitude.On this basis,the modulation principles of phase modulator,Mach-Zehnder modulator and I/Q modulator are studied.For the sake of accuracy,experiments of high linearity sweep signal modulation are carried out.The time aperture reaches 4.4ns and the FOM exceeds hundreds,which are much larger than the traditional electro-optical phase modulation time lens.In addition,two methods for extending the linear frequency sweeping time-lens bandwidth are also studied.Aiming at the application of time lens in optical signal processing,an optical pulse shaping simulation system based on linear sweep time lens is constructed.In the aspect of temporal imaging,we investigate the scaling factor range of the time lens for a 1 ps Gauss pulse.And then combining the modulation process of I/Q modulator,the influence of various factors in temporal imaging is studied.The simulation results show that highorder phase terms and misfocus are the main causes of temporal aberration.In the aspect of time-domain Fourier transformation,the Fourier transformation process of time lens is simulated and analyzed.Based on the invariance of pulse spectrum transmission in dispersion system and the correspondence between the time domain waveform and the spectrum envelope of the Gauss pulse,a distortion-free transmission system of the Gauss pulse based on the conversion from frequency domain to time domain through Fourier transformation is realized.更多还原