提高超短激光脉冲传播过程记录精度的研究

发布时间：2017-12-28 05:00

本文关键词：提高超短激光脉冲传播过程记录精度的研究　出处：《深圳大学》2017年博士论文　论文类型：学位论文

【摘要】：超短脉冲激光已经被广泛应用于包括超快现象研究、精密材料加工、超精密外科手术、光通信和高新技术领域等科研和生活的各个领域,并推动了物理、生物、化学、材料和信息科学等领域的全新发展。超短脉冲激光在介质中的传播是超短脉冲激光技术的基础。因此,实现超短脉冲激光传播行为的记录和观察,对于各个领域的研究和应用都具有重要的价值和意义。通过观察超短脉冲激光的传播行为,不仅可以证实超短脉冲激光传播的相关理论和实验结果,还有助于发现、理解和完善地阐述超快过程和超快现象的动力学机制,有助于阐明高效材料加工的条件和优化激光加工中激光光束的控制,有助于阐明纳米手术中脉冲传播的最优条件,有助于应用于光子网络中光学器件的表征和机理研究,有助于分析和发展用于高性能光通信的光学器件和系统。本论文主要对能够实现超短脉冲传播过程记录和观察的时间分辨超快测量技术进行了深入、系统地研究,提高了超短激光脉冲传播过程的记录精度。本论文的主要工作创新包括以下几个方面:1.本文以透射型飞光全息记录为例,对再现脉冲波前畸变进行分析,并采用优化成像参数和引入柱透镜的方法提高了飞光全息记录的精度。飞光全息记录可以通过单次实验得到脉冲传播的空间和时间连续的动态图像,实现脉冲传播的直接可视化观察。但由于某一时刻脉冲波前截面通过散射器件产生的物光波前包含不受影响的原始波前和各方向出射的散射光波,因此全息图上与参考光同时到达(光程差小于相干长度)形成干涉图样的物光点并不严格对应于该脉冲波前截面上的点,导致再现脉冲波前产生畸变。由数值模拟结果可知,再现脉冲波前畸变随d(平行放置的散射平面和记录介质平面之间的间距)和θO(待测脉冲倾斜入射散射平面的角度)的增大而减小。因此,选取较大的d和θO,可以极大地减小再现脉冲波前在时间方向(全息记录介质表面脉冲传播的方向)上的畸变,此时来自脉冲截面上各点散射光引起的空间方向(在全息记录介质表面上与时间方向垂直的方向)上的互相影响仍然存在,全息图上一点再现出的脉冲形状无限接近于一条在时间方向上有一定宽度的直线。另一方面,通过引入一个柱透镜,可以在不影响记录脉冲传播过程的同时,极大地减小散射光在空间方向上的影响。2.提出DMD STRIPED FISH技术,与STRIPED FISH技术相比,可以在将CCD空间带宽积的利用率提高大约一倍的同时,极大地提高分幅速率。STRIPED FISH技术可以实现超短脉冲场时空分布的单次测量,但其子全息图的空间带宽积和带通滤波器对衍射光束的波长选择的自由度之间存在消长关系。通过在STRIPED FISH实验装置中加入数字微镜器件(DMD),使子全息图位置独立于波长选择,从而可以在实现CCD空间带宽积利用率的最大化的同时,极大地提高分幅速率。此外,结合电光采样技术,对THz脉冲的三维时空电场分布的单次测量进行了模拟,结果表明重建出的电场分布与原始分布基本一致。3.提出双探测频域剪切干涉技术,与频域全息成像(FDH)相比,在某些应用情况下具有更好的准确性和稳定性。双探测频域剪切干涉技术利用两束存在相对时间延迟的时频特性相同的线性啁啾脉冲共同探测超快相位,并利用迭代的方法进行相位重建。在待测相位持续时间较大的情况下,由于频谱仪的分辨率限制,Ⅰ类FDH(参考脉冲经过介质)无法准确测量及再现出待测超快相位。与之相比,双探测频域剪切干涉技术和II类FDH(参考脉冲不经过介质)不受到待测相位持续时间的影响,可以更为准确地测量及再现待测相位。而与II类FDH相比,双探测频域剪切干涉技术不需要额外的步骤测量介质色散引起的相位,且不会由于探测脉冲经过而参考脉冲不经过介质导致相位测量的稳定性和准确性容易受到环境的影响(尤其是对于空间分布相位的测量)。通过对太赫兹(THz)脉冲信号自由空间时域波形测量的实验结果表明,在有效探测时间宽度范围内,双探测频域剪切干涉技术测得的结果与II类FDH的基本相同,具有较高的准确性。4.提出消色散的光谱相位相干直接电场重建(SPIDER)的相位重建算法。SPIDER是一种能够快速和准确地测量超短激光脉冲参数的光谱剪切干涉测量技术。在传统的SPIDER系统中,待测脉冲的复制脉冲对之间的色散不平衡会导致相位测量误差。针对该误差,提出了一种消色散的相位重建算法,可以极大地提高待测脉冲的重建精度。数值模拟和实验结果都表明,利用消色散的准确算法可以极大地提高重建相位和预设相位的一致性。而相较于色散平衡的复杂结构,利用消色散的准确算法在保持实验结构简单的同时,还可以实现更高的重建精度。
[Abstract]:Ultrashort pulse laser has been widely used in various fields including scientific research, life and ultrafast phenomena precision materials processing, ultra precision surgery, optical communication and other high-tech fields, and promote the full development of new physics, biology, chemistry, materials science and information. The propagation of ultra short pulse laser in the medium is the basis of ultra short pulse laser technology. Therefore, it is of great value and significance for the research and application of various fields to record and observe the propagation behavior of ultrashort pulse laser. Through observe the propagation of ultrashort laser pulses, not only can confirm the related theoretical and experimental results of ultrashort pulse laser propagation, but also helps to identify, understand and improve on the ultrafast process of ultrafast phenomena and dynamic mechanism, a help to clarify, material processing and control optimization of laser beam in laser processing, help to elucidate the nano operation optimal pulse propagation conditions, characterization and Study on Mechanism of photonic devices used in optical network, is helpful to the analysis and development of optical devices and systems for high performance optical communication. In this paper, the time resolved ultrafast measurement technology that can record and observe ultrashort pulse propagation process is studied deeply and systematically, which improves the recording accuracy of ultrashort laser pulse propagation process. The main works of this paper include the following aspects: 1.. In this paper, the transmission wavefront hologram is taken as an example to analyze the reconstructed wavefront aberration, and the accuracy of flying holographic recording is improved by optimizing the imaging parameters and introducing the cylindrical lens. The flfly holographic recording can get the continuous dynamic image of the space and time by the single experiment, and realize the direct visual observation of the pulse propagation. But because of a moment produced by the scattering cross section pulse wavefront device consists of object wave front is not affected by the original wavefront and light scattering in all directions, so the hologram and the reference light arrived at the same time (optical path difference is less than the coherence length) and the formation of light interference pattern does not strictly correspond to the pulse front section the point, lead to the reappearance of pulse wavefront distortion. The numerical simulation results show that the reconstructed wavefront aberration decreases with the increase of D (the distance between the parallel placed scattering plane and the recording medium plane) and theta O (the angle of the scattering plane to be measured). Therefore, choosing the bigger D and 6 O, can greatly reduce the reappearance of pulse wavefront in the time direction (holographic recording medium surface pulse propagation direction) on the distortion, this time from the space section of each point on the direction of pulse light scattering caused by (in the holographic recording medium on the surface and the direction perpendicular to the direction of influence on each other) still, the hologram a pulse shape reproduce infinitely close to a straight line in the time direction with a certain width. On the other hand, by introducing a cylindrical lens, it can greatly reduce the influence of the scattered light on the spatial direction without affecting the propagation of the recording pulse. 2., put forward the technology of DMD STRIPED FISH. Compared with STRIPED FISH technology, it can increase the utilization rate of CCD space bandwidth product about twice, and greatly increase the rate of framing. The STRIPED FISH technology can achieve the single time measurement of the spatio-temporal distribution of ultrashort pulse field, but the spatial bandwidth product of its sub hologram and the band pass filter have a growth and decline relationship between the wavelength of the diffraction beam and the degree of freedom of the wavelength selection. By adding digital micromirror device (DMD) into STRIPED FISH experimental device, the location of sub holograms is independent of wavelength selection, so that the utilization rate of CCD bandwidth product can be maximized and the framing rate can be greatly improved. In addition, combined with electro-optic sampling technology, we simulated the single time measurement of three dimensional time and space electric field distribution of THz pulse. The results show that the reconstructed electric field distribution is basically consistent with the original distribution. 3. the dual detection frequency domain shear interference technique is proposed. Compared with the frequency domain holography (FDH), it has better accuracy and stability in some applications. The dual detection frequency domain shearing interferometry technology uses two linearly time-varying chirped pulses with the same time delay characteristics to detect the ultrafast phase together, and uses iterative method to reconstruct phase. Due to the limitation of the resolution of the spectrum analyzer, the first class FDH (reference pulse passing through the medium) can not accurately measure and reproduce the ultrafast phase to be measured under the condition of larger phase duration. In contrast, dual detection frequency domain shearing interferometry and II class FDH (reference pulse without medium) are not affected by the duration of the measured phase, and can be used to measure and reproduce the measured phase more accurately. Compared with II FDH, double frequency interference detection technology does not need the shearing phase measurement of dielectric dispersion caused by additional steps, and not because of the detection pulse after the reference pulse without phase medium causes the stability and accuracy of measurement easily affected by environment (especially for measuring the spatial distribution of the phase). The experimental results of the free space time domain waveform measurement of terahertz (THz) pulse signal show that within the range of effective detection time, the result of dual detection frequency domain shearing interferometry is basically the same as that of class II FDH, and it has high accuracy. 4. proposed achromatic spectral phase coherent direct electric field reconstruction (SPIDER) phase reconstruction algorithm. SPIDER is a spectral shearing interferometry technique that can measure the parameters of ultrashort laser pulses quickly and accurately. In the traditional SPIDER system, the unbalanced dispersion of the duplicated pulses between the pending pulses will lead to the phase measurement error. According to the error, presents an achromatic phase reconstruction algorithm can greatly improve the reconstruction accuracy of the measured pulse. Both numerical simulation and experimental results
【学位授予单位】：深圳大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TN24

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