飞秒激光多维信息存储关键技术研究

发布时间：2018-08-26 14:34

【摘要】：现代科技对数据容量需求的急速增长使超高密度信息存储技术成为当代信息技术领域重要的研究课题。多维信息存储改变了原有光存储技术依靠缩短激光波长和增加物镜数值孔径来提高存储密度的传统思路,在几何三维空间之外，，选择其他可以影响数据写入和读取的物理特性参量建立独立的坐标系,可以将多重信息记录到存储介质的同一物理空间上,并实现独立的读取,从而增加信息存储的维度。多维信息存储技术可实现的存储容量大,控制灵活方便,已成为下一代光存储技术发展的重要方向之一。本文结合飞秒激光双光子吸收的三维高分辨优势和偶氮苯材料的光致异构取向重分布特性,发展了偏振多元多阶信息存储技术,并对其中的关键间题进行了理论和实验研究。首先,介绍了偶氮苯的双光子光响应性质及机理,包括双光子光致异构、光致取向和光致取向烧孔等；对双光子光致异构速率方程和光致取向速率方程分别进行了描述；对于其中最重要的光致各向异性性质——光致双折射进行了理论分析和实验测量；对研究非线性光学特性的Z扫描方法进行了介绍,并对实验结果进行了分析。其次,搭建了飞秒激光双光子偏振存储系统并实现了偏振多元信息存储；分别利用偏振透射光读出,偏光读出和反射式扫描共焦读出三种方式验证了利用飞秒激光实现可擦除的偏振多元存储的可行性：存储密度理论值可以达到250Gb/cm3;还对存储过程中曝光剂量对信息点强度和大小的影响进行了实验研究和理论分析,为写入参数的进一步优化提供依据。另外,双偶氮苯poly(M2BAN-co-MMA)聚合物的偏振存储过程中,当曝光量超过特定阈值时,会出现灰阶低于背景的暗点。本文利用这一性质实现了偏振多阶信息存储：同时通过对与入光曝光时间的控制实现了9阶信息存储,并讨论了多阶信息存储中的影响因素；对偏振飞秒激光在双偶氮苯聚合物薄膜中诱导产生表面形貌进行了深入的理论模型研究和实验分析,结果表明电场梯度力模型可以很好的解释偏振激光引起的表面形貌；并且对不同曝光条件下的偏振存储进行了详细的讨论。最后,论文进行了基于空间光调制器的三维并行存储技术的初步研究；详细介绍了空间光调制器的结构以及调制机理；设计了三维计算全息算法并在此基础上实现了多层图像的设计和重现,验证了三维动态并行数据存储的可行性；同时考虑了折射率失配引起的离焦和球差对三维动态并行存储的影响并提出在全息算法迭代过程中进行补偿,为下一步实现并行多维信息存储和高效高分辨跨尺度全息并行加工奠定了基础。
[Abstract]:With the rapid growth of the demand for data capacity in modern science and technology, ultra-high density information storage technology has become an important research topic in the field of information technology. Multi-dimensional information storage has changed the traditional idea that the original optical storage technology can improve the storage density by shortening the laser wavelength and increasing the numerical aperture of the objective lens. The independent coordinate system can be established by selecting other physical characteristic parameters which can affect the data writing and reading. The multiple information can be recorded into the same physical space of the storage medium and read independently, thus increasing the dimension of information storage. Multi-dimensional information storage technology can achieve large storage capacity, flexible and convenient control, which has become one of the important directions of the next generation optical storage technology. In this paper, based on the three-dimensional high resolution advantage of femtosecond laser two-photon absorption and the redistribution of photoinduced isomerization of azobenzene, the multi-order information storage technology of polarization is developed, and the key problems are studied theoretically and experimentally. Firstly, the two-photon photoresponse properties and mechanism of azobenzene are introduced, including two-photon photoisomerization, photo-orientation and photo-orientation hole burning, and the two-photon photoisomerization rate equation and photo-orientation rate equation are described respectively. The most important photoinduced anisotropy, photoinduced birefringence, is analyzed theoretically and experimentally, and the Z-scan method for studying nonlinear optical properties is introduced, and the experimental results are analyzed. Secondly, a femtosecond laser two-photon polarization storage system is built and the polarization multi-component information storage is realized. The feasibility of erasable polarization multivariate storage using femtosecond laser is verified by three ways of polarized readout and reflection scanning confocal readout: the theoretical value of storage density can reach 250 GB / cm ~ 3, and the information of exposure dose during storage is also given. Experimental study and theoretical analysis of the effects of point strength and size are carried out. It provides the basis for further optimization of write parameters. In addition, in the polarization storage process of poly (M2BAN-co-MMA) polymer, when the exposure exceeds a certain threshold, a dark spot with gray scale below the background will appear. In this paper, the polarization multi-order information storage is realized by using this property. At the same time, the ninth order information storage is realized by controlling the exposure time with the incoming light, and the influencing factors in the multi-order information storage are discussed. The surface morphology induced by polarization femtosecond laser in the diazobenzene polymer film was studied and experimentally analyzed. The results show that the electric field gradient force model can explain the surface morphology induced by polarized laser. Polarization storage under different exposure conditions is discussed in detail. Finally, the paper makes a preliminary study of 3D parallel storage technology based on spatial light modulator, and introduces the structure and modulation mechanism of spatial light modulator in detail. The 3D CGH algorithm is designed and the multi-layer image is designed and reproduced on the basis of which the feasibility of 3D dynamic parallel data storage is verified. At the same time, the influence of defocus and spherical aberration caused by refractive index mismatch on 3D dynamic parallel storage is considered, and compensation is proposed in the iterative process of holographic algorithm. It lays a foundation for the next step to realize parallel multidimensional information storage and efficient high resolution cross scale holographic parallel processing.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2012
【分类号】：TP333

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