新型波导多层光存储信息读出光学系统设计

信息读出光学系统是波导多层存储方法的重要组成部分,从几何光学角度,提出了两种信息读出光学系统的理论设计,并对两种系统的特点进行了实验研究,结果表明两种光学系统都是可行的,而且对波导多层光存储的进一步研究及实用化都有一定的参考价值。     

集成光学平板光盘读出头研制

采用集成光学方法,将非球面消球差双凸波导透镜、双光栅会聚光波导透镜、光波导转向棱镜单片集成在铌酸锂基底上构成光学平板光盘读出头.集成光学平板光盘读出头克服了微透镜光盘读出头体积大、组装复杂的不足,实现了光盘读出头的集成化,提高了系统的可靠性.光斑理论值0.475 μm,实测值0.67 μm.     

超分辨近场结构光盘的传统以及差分读出方法研究

利用标量衍射理论和角谱方法,针对超分辨近场结构光盘存储系统建立了简单物理模型,并提出了超分辨近场结构光盘的读出信号仿真计算方法.通过对比实际测试信号与模拟信号,证明了该读出信号计算方法的可行性.此外,针对超分辨掩膜层对不同功率入射激光响应不同的特性,分别分析了单轨道和三轨道记录符在高、低功率两束激光读出下的差分信号.数...     

超分辨技术在光盘中的应用研究

超分辨技术是一种无需用减小波长或增大数值孔径的方法减小记录点尺寸而能读出超过衍射极限信号从而有效增加存储密度的一种方法，超分辨可以通过调整光学系统或者调整光盘的结构来实现，在超分辨光盘中，超分辨是基于掩膜的光学性质随入射激光强度的非线性变化而实现的，在磁光盘中第一次引入超分辨技术后，超分辨技术的应用有了很大发展，在目前是提高光盘存储密度的有效方法，在各类光盘中都有良好的应用，近场超分辨技术的出现使相变光盘的超高密度记录和读出成为可能，文章综述了超分辨光盘的发展现状和发展方向。     

多阶游程长度受限编码的光盘读出信号

多阶游程长度受限(ML-RLL)编码可以在保持原有记录符尺寸和记录单元数量的情况下将CD光盘存储容量提高2.4倍。借助标量衍射理论建立了多阶游程长度受限记录符的计算模型,对采用多阶游程长度受限编码的CD光盘的读出信号进行了仿真分析。结果表明,记录坑长度的变化对读出信号幅值影响较小,有利于将记录坑长度和记录坑的宽度两个参数进行分离检测,但在3T长度、不同宽度的记录坑相连的情况下,从读出信号中很难分辨出记录符的分界位置。     

蓝光相变光盘的多层膜结构设计

为了使光盘获得优良的记录／读出性能并能够长期稳定地使用，必须优化设计相变光盘的多层膜结构。采用自行设计的模拟分析相变光盘读出过程设计软件，从光学角度出发模拟计算了蓝光(405nm)相变光盘的膜层结构，研究了多层膜系的反射率和反射率对比度等光学参量与各层膜厚度和槽深的关系。研究得出的最佳多层膜结构为：下介电层／记录层／上介电层／反射层的厚度对于台记录为100nm／10nm／25nm，／60nm，而对于槽记录则为140nm／15nm／30nm，／60nm，槽深为50nm。模拟计算结果对于将来高密度蓝光相变光盘的制备具有一定的指导意义。     

掺铒聚合物狭缝波导放大器的增益特性研究

设计了一种高浓度稀土铒掺杂聚合物填充硅狭缝结构的平面光波导放大器（工作波长1 550 nm,泵浦波长1 480 nm）,能够在低泵浦下获得高增益,可以应用于硅基光互联的损耗补偿。通过扫描电镜照片观察发现,合成的铒掺杂聚合物材料具有良好的纳米狭缝填充能力。考虑铒离子的合作上转换和激发态吸收,利用铒离子四能级跃迁模型,建立原子速率方程和光功率传输方程,数值仿真分析了聚合物光学性质、狭缝波导结构参数及信号光泵浦光功率等放大器增益特性的影响因素。这种具有纳米截面尺寸的光波导放大器,获得4.5 dB的信号光相对增益仅需要1.5 mW的泵浦光,展现了良好的集成光学应用前景。为了进一步提高增益,引入了多层狭缝结构,四层狭缝波导的重叠积分因子比一层狭缝的高42%。     

金属包层渐变折射率介质光波导的传输特性与损耗

用金属包层介质光波导损耗的微扰理论及藉助多层近似法用递推公式分析渐变折射率波导传播常数的方法,对几种类型的金属包层渐变折射率介质光波导的传输特性与损耗进行分析和讨论,得到了与精确数值计算结果相吻合的结果.     

光盘存储读出信道的实现

通过构建适合于硬件电路实现的读出信道数学模型以及对光存储系统中存在的噪声、抖晃和扰动的分析,在FPGA(Field programmable gate array)硬件平台上,实现了对任意二阶至四阶记录光盘读出RF(Radio frequency)信号的模拟实时连续输出。在信道模拟的硬件算法设计中,采用了四倍频的方法和基于ROM(Read-only memory)查找表的方法实现了100Mbit高速情况下的卷积运算。设计结果得到了逼真的网眼图,验证了模型的正确性,且已作为光盘系统后续信号处理模块的信源,加快了光盘系统研制开发的步伐。     

质子交换光波导生长机理的研究

对质子交换光波导生长机理进行了研究并给出了波导层厚度的计算公式。     

A simultaneous generation of QKD and QDC via optical memory array for distributed network security

We propose a novel system of a simultaneous generation of continuous variable quantum key distribution (QKD) and quantum dense coding (QDC) via an optical memory array. The optical memory system is formed by using an array waveguide incorporating a nano-ring resonator, whereas the different spatial light modes can be generated and stored within an optical memory unit. The polarized photon is formed and stored within a storing device, i.e. a ring resonator, whereas the different time slot entangled photons can be generated, transmitted and detected by the different subscriber in the distributed networks. By using the optical memory concept, the continuous variable quantum key distribution is provided. Furthermore, the use of quantum dense coding via time division multiplexing paths, i.e. different time slot, is also plausible. The advantage of the proposed system is that the quantum key distribution can provide the network top security with high capacity and safety, which is the large demand of usage in the public networks.     

Polymer waveguide with integrated reflector mirrors for an inter-chip link system

A polymer waveguide with integrated reflector mirrors is presented for an inter-chip link system. The cost-effective and repeatable technology for the integration of a polymer multimode waveguide and out-of-plane 45° reflector mirrors was developed for optical coupling between the light-sources and the light-detectors. This method enabled us to fabricate the waveguides and 45° reflector mirrors using a one-shot embossing process for inexpensive mass production. The optical inter-chip link system consisted of a metal optical bench, a module printed circuit board (PCB), a driver/receiver IC, a vertical-cavity surface-emitting laser (VCSEL)/photo-detector (PD) array, and an optical waveguide composed of integrated reflector mirrors. The presented data transfer measurements of the optical inter-chip link system are shown to be successful at a data rate of 5 Gb/s.     

A novel multi-optical/quantum memory and encoding system using multi-photon generation

We propose a novel system of an optical/quantum memory generation, which can be used for multi-optical/quantum memory applications. The large bandwidth of a single pulse is generated using a soliton pulse in a Kerr-type nonlinear medium, i.e. a nonlinear waveguide. The generation of the localized temporal and spatial soliton pulses within the nano-waveguide is achieved. The free spectrum range enhancement of the generated multi-soliton signals can be formed and achieved using the nano-waveguide incorporating the Mach Zhender Interferometer (MZI). The different light path of the soliton pulses is introduced by the delayed lines of the interferometer. This improves the wavelength free spectrum range, where the different entangled photon pairs can also obtained. Furthermore, the generated photons can be filtered and stored within a system, where the storage of single or multi-photons using the proposed system can be achieved, which in turn can be used for multi-optical/quantum memory applications.     

Partially and fully cured thin film photoresist waveguides for integrated optics

A systematic and detailed study of waveguide fabrication and characterization of a commercially available (from Shipley) photoresist is reported. Various waveguide properties such as refractive index, optical losses, waveguide thickness, dispersion and birefringence are reported. Effect of temperature of guide formation, curing (partial and full) and UV exposure on these parameters is also presented.     

GeSi/Si多量子阱红外探测器波导结构的理论计算

本文采用传输矩阵的方法计算了Ge_xSi_1-x/Si量子阱红外探测器结构参量对多量子阱波导结构模场分布,光场限制因子和有效吸收系数的影响,并给出了优化设计的结果.     

Real-space observation of nanojet-induced modes in a chain of microspheres

The three-dimensional real-space observation of photonic nanojet-induced modes in a chain of microspheres with different diameters is reported. The optical transmission properties of a chain of microspheres are studied by using high resolution finite-difference time-domain calculation. The photonic nanojet-induced modes in different chains of microspheres are measured by using a scanning optical microscope system with an optical-fiber probe. We observe the photonic nanojet-induced modes from optical microscope images for chains of 3 μm, 5 μm, and 8 μm microspheres deposited on a patterned silicon substrate. The incident beam can be periodically reproduced in chains of dielectric microspheres giving rise to lossless periodically optical focusing with period of two diameters. Detailed theoretical and experimental data on the transmission, scattering loss, and field-of-view are presented. This waveguide technique can be used in biomedical microscopy, ultra-precise laser process, microfluidics, and nanophotonic circuits.     

Dispersion characteristics of complex refractive-index planar slab optical waveguide by using finite element method

In this paper, finite element method (FEM) mode analyses of planar slab optical waveguide having complicated refractive index profile are presented. We try to estimate the dispersion graph, mode cut-off condition, group delay and waveguide dispersion for the case of α-power and chirped-type refractive index profile. In order to obtain the more accurate result, we have derived the higher-order polynomial, which establishes the suitable relationship between b and V for different profile of optical waveguide. On the basis of the derived polynomials, the waveguide dispersion is analyzed for different type of refractive index profile waveguide. Our study shows that the waveguide dispersion can be substantially reduced when we deployed the optical waveguide having linearly chirped-type refractive index profile. Earlier too, the arbitrary refractive index profile has been analyzed but to the best of our knowledge chirped-type refractive index profile has not been analyzed till date for the case of planar slab optical waveguide.     

Integrated Planar Waveguide Demultiplexers for High-Density WDM Applications

A review is presented of state-of-the-art optical planar waveguide demultiplexers (DEMUXes), that is, phasars (arrayed waveguide) and etched grating devices designed for high-density (narrow channel spacing) wavelength division multiplexing (WDM) systems. Their advantages and disadvantages are discussed in comparison with other techniques for demultiplexing WDM signals. The advances made in their performance are reviewed, and ultimate limitations, set by technological constraints, are proposed. Finally, a comparison is made of the advantages and disadvantages of etched grating as opposed to phasar planar waveguide DEMUXes.     

Multi-wavelength filtering in side-coupled cascaded-cavities systems

We theoretically investigate an optical system, which consists of a waveguide side-coupled to a cascade of cavities, the filtering properties by the time domain coupled-mode theory. In such a system, the filter operating bandwidth and the width of transmission peaks are completely determined by the mutual coupling coefficients between the cavities. The characteristics are numerically demonstrated in photonic crystals by the finite-difference time-domain method.