衍射光学在光通信和光学信息处理中的应用
文献类型：学位论文
| 作者 | 滕树云 |
| 学位类别 | 博士 |
| 答辩日期 | 2004 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 刘立人 |
| 关键词 | 菲涅尔衍射 夫朗和费衍射 光学超分辨 部分相干光理论 泰伯效应 藕合波理论 |
| 其他题名 | Applications of the diffraction in optical communication and optical information processing |
| 中文摘要 | 衍射适用于光波由光源发射到接收的整个过程，实际中最为常见的是光波通过障碍物后的衍射。由于衍射物体的存在，衍射后光波的振幅、位相发生变化，进而影响到光波衍射特性的改变，这可能给光波的某些实际应用带来负面影响。反之，我们也可利用这一特性，借助于衍射体获得在光通信和光学信息处理中需要的光波，这也是本文的研究目的。衍射光束质量是实现激光通信的前提条件之一，因此研究激光光束的传输以及整型具有实际意义。光源的相干性会影响到光束的衍射特性，研究光源相干性的影响将有助于预测光束测量结果，而作为时间相干性的超短脉冲光源由于驰豫时间极短和丰富的谱分布具有广阔的应用前景，它经信息存储重要光学元件体光栅的衍射也引起人们的注意。针对目前关于光束衍射在微光学、信息编码、信息存储以及光通信中的应用及研究中存在的问题，我们开展了如下几方面的理论和实验研究工作：（1）针对光在实际反射或传输中要受到衍射孔径或衍射光学元件有限边界的限制，本文首先借助于贝塞尔函数的性质理论分析了圆孔衍射，包括沿传输轴上的衍射、圆孔边界投影处的衍射以及横向衍射，并提出了圆孔衍射的三维光强分布的近似解析解。利用菲涅尔的半波带理论对圆孔的横向衍射和轴上衍射的内在联系进行了合理的解释。其次我们也研究了有波差的光束经圆孔的衍射，讨论了波差对圆孔的菲涅尔衍射、夫朗和费衍射以及远场发散度的影响。（2）在远距离激光通信和诸多信息处理的应用中，激光器的工作模式大多为基模，该模式下的光束可用高斯光束来描述，为此我们研究了圆孔限制下高斯光束在菲涅尔衍射区和夫朗和费衍射区的衍射。发现了孔径受限高斯光束衍射与平行光照明下同尺寸口径孔径光阑衍射一致的等价条件，这为高斯光束衍射的简化处理提供了理论依据。此外借助于菲涅尔的半波带理论对受限高斯光束的轴上衍射光强分布以及横向衍射分布轮廓进行了物理连释。对有波差的高斯光束的传输进行了讨论，分析了波差对衍射受限高斯光束的近场衍射和远场光强以及远场发散角的影响。（3）针对光束在微光学中的应用，本文特别研究了衍射极限范围内高斯光束的空间整型。针对G-S算法在小范围内运行时收敛速度慢的特点，本文提出了反向传递优化算法获得位相补偿的衍射光学元件的结构，将高斯光束整型为衍射极限范围内的平顶分布、环状分布以及两环结构的衍射光强分布。此外，能量高而发散度小的超衍射极限激光光束在远距离激光通信中可获得较高的信噪比，为此本文利用光学超分辨技术将高斯光束进行有效压缩，使整型后的光束发散度超过衍射极限且能量密度提高，并提出了检测该类光束质量的衍射中场测量法。（4）部分相千光理论适用于任意发光类型光源发出的光波的传输，而光栅的泰伯效应又在光学信息处理中具有举足轻重的地位，为此本文首次利用部分相千光理论研究了光源的相干性对光栅泰伯效应的影响，得到了适用于任意发光类型多色光源照明下光栅菲涅尔衍射光强的一般公式，并分别对光源的发光尺寸和频谱分布对光栅泰伯效应的影响进行了讨论。研究中我们发现了扩展光源的发光尺寸对光栅衍射光强分布的平滑作用。理论预言并证明具有相同谱分布的超短脉冲激光光源和多色连续照明光源对光栅自成像的影响完全等价性的结论。此外研究表明脉冲激光照明下光栅衍射在适当条件下能够得到与输入轮廓完全相同的时间脉冲。实验中对多种频率激光照明下光栅衍射以及不同发光尺寸的扩展光源照明下光栅的衍射光强分布进行了观察和测量，印证了上述理论结果。（5）超短脉冲激光光束包含丰富的频谱，而体光栅具有波长选择性的特性，不言而喻，体光栅必将限制超短脉冲激光光束衍射的频谱成分。本文首次研究了考虑介质色散效应时超短脉冲激光光束经体光栅的衍射。依据Kogelink藕合波理论，得到了衍射和透射信号的光谱分布、时间分布以及衍射效率的表达式。定义了体光栅波长选择性的数学表达式，由此讨论了体光栅参数如光栅间距、光栅调制度和光栅厚度以及入射条件对上述衍射特征量的影响。数值计算的结果表明通过调节体光栅的参数可以控制衍射光束的频谱宽度进而获得动态脉冲轮廓。超短脉冲激光光束照明体光栅时的衍射频谱的实验测量结果有效地印证了理论分析和数值计算得到的结论。（6）此外还进行了卫星激光通信的其它研究工作。 |
| 英文摘要 | The diffraction phenomenon exists during the wave propagation process from the wave emission to the signal receiving. In fact, it usually points to the diffraction of the wave through the obstruction. Because the diffraction object changes the amplitude and the phase of the incident wave, the diffraction characteristics of the wave after the diffraction object vary correspondingly. It maybe bring the negative influence on the practical applications of the beam, in reverse, we can make it helpful for the applications of the beam, for an example, recurring to the diffraction object, we can obtain the wave available for the optical communication and the optical information processing, and this is the aim of this thesis. Since the quality of the beam is one precondition of the laser communication, the study about the propagation and the shaping of the laser beam is much more significant. The coherence of the source influences the diffraction characteristic, and the investigation about it will be helpful for the beam measurement. The ultrashort pulsed laser as a source with temporal coherence has widely application because of the ultrashort duration time and the abundant spectrum, and now its diffraction by the volume grating has been attracted many attentions. Aiming to the some applications of the diffraction in the micro-optics, the information code and storage and optical communication, and the existent problem thereinto, we perform the following works. (1) Since the beam is inevitably limited by the diffraction aperture or the boundary of the diffraction element during the propagation, we analyze theoretically the diffraction of the circular aperture and give the analytical solution of the three-dimensioned diffraction recurring to the characteristic of Bessel function. After studying the axial diffraction and the diffraction along the boundary of the circular aperture, we present the approximate analytic solution of three-dimensioned diffractive intensity. On the basis of the Fresnel zone theory, we explain the relation of the transverse diffraction and the axial diffraction. In addition, we study the diffraction of the beam with the wave error, and discuss the influence of the wave error on the Fresnel diffraction, Fraunhofer diffraction and the far-field divergence. (2) Comparing to the parallel light, the Gauss-shaped beam is close to the practical one emitting from the basic mode laser used in far-distance laser communication and the information processing, thus we analyze the Fresnel and Fraunhofer diffraction of Gaussian beam by the circular aperture. Then we find the equivalence condition of the diffraction of Gaussian beam limited by the circular aperture and that of the parallel with the same diffraction boundary, which provides the theoretic foundation to simplify the diffraction of Gaussian beam. By use of the Fresnel zone theory, we explain the distribution rules of the axial diffraction and the transverse diffraction. Moreover, we analyze the propagation of the beam with wave error and discuss the influence of the wave error on the diffraction and the divergence. (3) Owing to the wide application of the beam in the micro-optics, we study especially the shaping of Gaussian beam in the diffraction-limited region. The phase structure of the compensative phase plate is determined according to the inverse-transformation-optimizing-algoritrmi presented in this thesis and the shaped beams including fiat-top beam, the annular beam and the beam with two annuli in diffraction-limited region are obtained. Furthermore, since the laser beam with high power and small divergence has big SNR (Signal-to Noise Ratio), which is very helpful for far-distance laser communication, we try to reduce the divergence of Gaussian beam recurring to the optical superresolution technology and we get successfully this beam beyond the diffraction limits. We also design a method, i.e., the diffraction medial field method to test and measure this kind of beam. (4) The theory of partially coherent light is available for the propagation of the beam with arbitrary coherence degree and Talbot effect of the grating has an important status in the optical information processing, so in this paper we also study the Fresnel diffraction of the grating illuminated by the partially coherent light. A general formula of Fresnel diffraction of the grating illuminated by the arbitrary coherent light is obtained. Then the influence of the size of the source and the width of the mcident spectrum on the Talbot effect is discussed. Among these discussions, we find the size of the source will smooth Talbot imaging of the grating and the influence of the different source with same spectrum on the diffraction of the grating is totally equivalent. Moreover, in the study of the diffraction of the grating illuminated by the ultrashort pulse laser, we find the same temporal profile as the mcident pulse can be obtained with the proper condition. The corresponding experiments are carried out and the experimental results conform well to the theoretic ones. (5) The ultrashort pulse laser possesses abundant spectral components, and the volume grating has the characteristic of the wavelength selectivity, so it seems that the volume grating must limit the diffraction of some incident spectral components. Here, we first study the diffraction of the volume grating with the dispersion effect read by the ultrashort pulse laser. On the basis of the coupled wave theory of Kogelnik, the formulas of the spectral and temporal distributions of the diffraction and transmission signals and the diffraction efficiency are obtained. After defining the mathematic expression of the wavelength selectivity of the volume grating, we discuss the influence of the parameters of the volume grating, such as the grating space, the grating modulation and the grating thick, and the incident condition on the above-mentioned physical quantities. The analysis shows that the diffraction pulse profile can be controlled by adjusting the parameters of the volume grating to change the spectrum distribution of the diffraction and the transmission signals. The corresponding numerical calculations are given. In the end, an experiment to measure the diffraction spectrum and the diffraction power is performed. (6) We also develop the research about the inter-satellite communications. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15429]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 滕树云. 衍射光学在光通信和光学信息处理中的应用[D]. 中国科学院上海光学精密机械研究所. 2004. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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