《论文中英文摘要.doc》由会员分享，可在线阅读，更多相关《论文中英文摘要.doc（6页珍藏版）》请在taowenge.com淘文阁网|工程机械CAD图纸|机械工程制图|CAD装配图下载|SolidWorks_CaTia_CAD_UG_PROE_设计图分享下载上搜索。
1、附件6论文中英文摘要作者姓名：陈沁论文题目：多边形微腔激光器和微腔滤波器的研究作者简介：陈沁，男， 1979年7月出生，2001年9月师从于中国科学院半导体研究所黄永箴研究员，于2007年8月获博士学位。中 文 摘 要以Internet为代表的国际互联网的发展，标志着全球信息化社会的到来。IP业务呈现爆炸性增长，约69个月就翻一番。面对如此高速增长的信息需求量，电子技术遇到严重的挑战。微电子器件到如今可以说到了登峰造极的地步，目前已经达到45nm的工艺水平。集成的极限将在不久的将来出现，而这是由电子的特性所决定的。光子作为信号的另一种载体，有着电子所没有的优势：宽带、高速、低损耗、无干扰。基于
2、上述发展背景，光子集成和光电子集成有了极大发展。集成化规模的提高对功耗的要求越加关注，发展低阈值、低功耗的微型激光源是必由之路。光学微腔同时具有极小的模式体积V和极高的品质因子Q，它的Q/V值要远远高于普通的光学谐振腔，成为微型激光器的首选。同时基于光学微腔的光学滤波器、光开光、光调制器和光延迟器等光电子器件在波分复用系统中也得到广泛关注并体现出优异的特性。它们的实用化将在光子集成和光网络方面起到极大的带动作用，对整个光信息技术的发展具有深远影响。不仅如此，光学微腔具有超高的品质因子，自然成为研究自发辐射控制和腔量子电动力学这个新兴研究领域的载体，在基础研究方面具有重要学术意义。在自发辐射控制
3、、低阈值单模激光器和高性能滤波器的研究中，另一类极具潜力的新材料和新器件是光子晶体。光子晶体在近十几年取得了迅猛的发展，成为国际学术界的研究热点和产业界积极开拓的新方向。本论文以光学微腔为出发点，以激光器和滤波器为两个主要研究方向，深入细致的开展了理论和实验的研究。微盘类腔由于体积小并具有超高的品质因子，近15年来成为低阈值激光器和控制自发辐射研究的热点。然而由于其回音壁(WG)模式非常强的模场限制和集中在圆周附近的模场分布使得很难实现方向性的高效率光输出，而且侧壁粗糙会造成完全简并模式的分裂。多边形微腔虽然也是利用腔边界的完全内反射来实现强光学限制，但是由于不同的对称性而具有特殊的模式性质。
4、正三角形腔的特点在于基横模的分布集中在腔内部，三个角区的场相对较弱，如果从一个顶角引出一条垂直底边的输出波导，可以容易的获得定向输出同时不会引起谐振腔的严重形变，因此非常适合制作低阈值和定向输出的微腔激光器。正方形腔具有和微盘可比拟的高品质因子WG模式，而且模式间距是同尺寸微盘的两倍，更容易获得稳定的单模工作，同时正方形腔在滤波器应用中由于具有更长的耦合长度，大大降低了工艺难度。本论文的工作主要围绕这两种微腔展开。在理论研究中，重点讨论了两种微腔结构的模式分布和品质因子的变化，并优化设计了光泵浦和电注入微腔激光器的结构，同时深入研究了微腔和波导的耦合作用和色散影响，提出了一种具有类行波模滤波响
5、应的变形正方形腔滤波器。实验研制中，采用普通光刻、干法刻蚀及选择性湿法腐蚀等工艺，制备了InGaAsP/InP材料的电注入正三角形腔激光器和光泵浦的正方形微腔。本论文还涉及光子晶体数值模拟软件的开发，这种新型微结构的研究成为了本论文有益的补充。各部分的研究工作和成果如下：在模式分析中，品质因子是一个重要的参数。对于具有超高品质因子的微腔，数值模拟获得准确的品质因子需要很长的计算时间。我们基于求解波动方程获得的正三角形腔模式分布解析解，通过近场远场转换，利用远场辐射理论方法计算了正三角形腔模式的品质因子，其结果与时域有限差分(FDTD)法的模拟结果吻合很好。为初步掌握腔内模式特性和定性分析提供了
6、快速有效的工具。在优化设计的带输出波导的正三角形微腔中，还发现与单模输出波导耦合效率更高的对称态可具有比简并的反对称态更高的品质因子，利于定向输出微腔激光器的低阈值工作。国际上首次获得电注入InGaAsP/InP材料的正三角形腔激光器的室温连续工作，其定向输出为微腔激光器的实用化展现了一种新的途径。采用普通光刻和感应耦合等离子体(ICP)刻蚀工艺制备了电注入的正三角形柱结构的激光器，谐振腔平面尺寸在1030m，柱高约4m。从输出波导的解理端面获得定向输出。激光器在室温下单模连续激射，边模抑制比达到25dB。通过比较光谱中模式峰间隔和理论的纵横模的模式间距，证实了我们的理论模型。我们还进行了激光
7、器的80-310K的变温测试，获得了阈值电流和温度的关系。理论和实验研究了正方形微腔中的模式特性。对变形正方形腔的模拟中，发现优化的圆角和切角变形，可使模式品质因子提高一个量级；而侧壁粗糙、矩形和菱形变形会造成WG模的品质因子降低到和非类WG模一个量级，导致模式间距减半。采用三维FDTD方法分析了三维正方形薄板腔的模式特性，并与等效折射率近似下的解析解和二维FDTD模拟结果作比较，发现等效折射率近似虽然能给出准确的模式波长，但是得到的品质因子偏低。并深入讨论了三维薄板结构中，支撑柱的尺寸和形貌对模式的影响，发现奇阶模由于在腔中心极弱的模场分布具有比偶阶模更高的品质因子。在优化结构中可以获得奇偶
8、阶模间的模式选择性，进一步增大模式间距，利于单模工作。实验上采用普通光刻和两步湿法腐蚀工艺制作了InP柱支撑的InGaAsP材料的正方形薄板微腔，腔边长520m。采用双光纤探测的手段进行了光泵浦的测试，在PL谱中观测到正方形微腔模式峰，和理论结果吻合。在微环滤波器中发现了分布模式耦合引起的耦合色散现象，对滤波器的设计具有重要的指导意义。采用FDTD法分析二维圆环形腔滤波器结构，发现了分布模式耦合引起的耦合色散会造成滤波器性能的严重退化，即谐振波长处可能出现的零下载和非谐振波长处强的能量下载，引起滤波器消光比和精细度的大幅降低。通过简单的耦合模理论分析两耦合直波导的传输特性，准确的预示了相同耦合
9、长度的跑道型滤波器的色散特性，并提出了利用非对称耦合波导结构消除分布耦合引起的这种过耦合现象。对于半径2m的输入输出波导时，消光比和精细度分别比对称波导结构提高了14dB和8倍。发现在优化设计的单个圆角和切角变形的正方形微腔滤波器中的类行波模滤波现象，展现了单个正方形腔滤波器在WDM系统中的应用潜力。与m的单个理想正方形腔滤波器比较，变形正方形腔滤波器的开关比和分光比分别获得14dB和15dB的提高。理论分析表明这种类行波模滤波现象是由于这种变形腔中存在两个相反对称性模式的简并，它们相差/2相位耦合导致了类似行波模的滤波特性。同时提出一种仅进行单个微腔模拟来优化滤波器结构的设计方法。当变形腔中
10、相同模指数和、对称性相反的两个模式发生简并时，基于这种变形腔的滤波器中将获得类行波模滤波响应，自由谱域由模指数和相差1的模式间距决定。开发了一套分析光子晶体能带结构、光子晶体微腔、光子晶体波导和光子晶体光纤的数值计算软件。成功的将Pad近似应用到光子晶体数值计算中，在模式品质因子达到1011时依然能够得到准确结果，较之国际上常用的FFT算法，计算时间和占用内存实现几个量级的减少。关键词： 光学微腔，微腔滤波器，光子晶体，半导体激光器，FDTD方法Study on Polygon Microcavity Lasers and Microcavity FiltersChen QinABSTRACT
11、In the last decades, the internet has been widely developed in the whole world, which indicates the coming of the information era. The IP services increase sharply and double every 6-9 months. In the face of high-speed increase of the information requirements, electronic technologies reach the bottl
12、e-neck. Nowadays, the minimum line width of microelectronic devices has reached 45nm. The limitation of the integration will come up soon, which is decided by the intrinsic characteristics of the electron. As another type of the signal transmission, the optical transmission has very large bandwidth,
13、 high speed, low loss and no interference. So photonic and optoelectronic integration is an indispensable direction and has a rapid development. With the increasing integration intensity, the requirement of the low power cost devices is much more exigent. One solution is the application of the micro
14、laser with ultralow threshold and power cost. Optical microcavities have both small mode volume V and high quality factor Q, their Q/V values are much larger than conventional optical cavities, which is the base to develop the microlaser. At the same time, optical channel drop filters, switches, mod
15、ulators and optical delayers based on optical microcavities have attracted many interests and show their excellent properties in the WDM system. The practical applications of these devices will bring the impetus of photonic integration and optical network, and promote the optical information technol
16、ogy. In addition, due to the ultrahigh quality factors, optical microcavities are naturally chosen as the carrier for the study on the enhancement/suppression of spontaneous emission and cavity quantum electronic dynamics, which is very important to the basic science. Photonic crystals are new mater
17、ials and devices with much potential in the control of spontaneous emission, low-threshold lasers and optical filters. In the last decades, it has been the highlight of the science research and the industrial development. On the base of optical microcavity, this dissertation has two main research to
18、pics: lasers and filters. The in-depth studies have been conducted both theoretically and experimentally. Due to ultrasmall volume and ultrahigh quality factor, microdisk has been the research focus in the field of low threshold lasers and the control of spontaneous emission for the last 15 years. H
19、owever, the directional emission is difficult to be realized because of the strong confinement of the WG modes concentrated near the circumference. Furthermore, the split of the intrinsic degenerate modes is caused by the roughness at the sidewalls, which is not fit for the single mode laser. Polygo
20、n microcavities have the same light confinement scheme by the totally internal reflectivity as the microdisk, however, the mode characteristics are diverse due to the different symmetry properties. Equilateral triangle resonator (ETR) has a C3v symmetry property, in which the field distribution of t
21、he fundamental transverse mode concentrates in the center of the resonator. By introducing an output waveguide from one of the vertices, the directional emission can be achieved without much degradation of the mode quality factors. It has great potential in the practical application of microlasers w
22、ith both low threshold and directional emission. Square resonator (SR) supports high quality factor modes as microdisk and the modes interval is twice that of microdisk of the same size. So it is attractive in the field of the single mode microlasers. In addition, as an optical filter, SR has a much
23、 longer coupling length than microdisk and microring, which releases the fabrication burden. The research work of this dissertation focuses on the two types of resonators. In the facet of theoretical work, we investigate the mode distribution and mode quality factor in ETR and SR, and optimize the o
24、ptically pumped and electrically injected lasers. In addition, we investigate the dispersive relation in the coupling between microcavity and waveguide and propose a deformed SR filter with traveling-wave filtering response. In the facet of experimental work, we fabricate the electrically injected E
25、TR microlaser and optically pumped SR on InGaAsP/InP wafer by using the conventional photolithography, dry etching and selectively wet etching. The development of photonic crystal simulation software is also included in this dissertation. As the research hot topic in the microscale structure, it is
26、a useful complement to the whole dissertation.The research work and achievements are expressed in the following:Mode quality factor is an important parameter in the mode analysis. For microcavities with ultrahigh quality factors, it is very difficult to obtain the accurate results. Based on the far
27、field emission method, we calculate mode quality factors of the ETR, where the radiation loss is obtained from the integral of the far field emission. The far field is deduced from the near field, which can be solved from the Maxwell equations with the appropriate boundary condition. The theoretical
28、 results of the mode quality factors are in good agreement with the numerical results by FDTD method. It gives a fast and effective tool to understand the mode characteristics qualitatively. Furthermore, we find that the symmetrical states, which have higher coupling efficiencies with the single mod
29、e output waveguide, can have larger quality factors than the antisymmetrical states in an ETR with an optimized output waveguide. It is interesting in the low threshold ETR lasers with directional emission.Continuous-wave electrical injection InGaAsP/InP ETR lasers with an output waveguide are reali
30、zed at room temperature for the first time to our knowledge. We fabricate the ETR lasers by conventional photolithography and Inductively Coupled Plasma Etching (ICP), where the etching depth is about 4m and the side length of the cavities is between 10 to 30m. The directional emission is obtained f
31、rom the cleaved edge of the output waveguide. Single mode lasing with more than 25 dB side-mode suppression ratio is obtained at 295K in an ETR laser with side length of 20m. The spacing of the peaks in the spectra agrees well with the theoretical mode interval. The theoretical longitudinal and tran
32、sverse mode characteristics are approved in the experiment. The temperature dependences of the threshold current and lasing wavelength are also measured from 80 K to 310 K. The mode characteristics are investigated for square resonators theoretically and experimentally. In a deformed square cavity w
33、ith circular and cut corners, the mode quality factors can even increase one-order under optimized parameters. The rough sidewalls, rectangular or rhombic deformation in a square cavity will degrade the quality factors of the WG-like modes to the same order as those of the non WG-like modes, then ha
34、lf the mode interval. For the free standing SR slab, the results from three dimensional (3D) FDTD simulations are compared with those obtained from the analytical solutions and two-dimensional (2D) FDTD under effective index approximation. We find that the mode frequencies and field distributions in
35、side the resonator obtained by 3D simulation are in good agreement with those from the 2D approximation. However, the quality factors obtained by 3D simulation are much larger than that by 2D simulation for the SR slab with the strong vertical waveguide. For the SR slab supported by a post, the mode
36、 frequencies and mode quality factors (Q-factors) are calculated as the functions of the size of the pedestal and the slope angle of the sidewalls of the square slab. Numerical simulation shows that the pedestal can result in mode selection between the WG-like modes with even and odd mode numbers. T
37、he odd modes have larger quality factors than even modes due to the different mode field distribution in the center of the resonator. SRs with side length of 5-20 m are fabricated by photolithography and two-step wet chemical etching technique, where the InGaAsP slab supported by an InP pedestal in
38、the center. The devices are tested by two fibers coupling system, one is for optical pumping and the other is for coupling the scattering light. The mode peaks are observed in the photoluminescence spectra, which are predicted by theoretical analysis.The influence of strong coupling due to distribut
39、ed mode coupling is studied for microring optical add-drop filters. In the 2D FDTD simulation of a racetrack filter, wide dips in the transmission spectra are observed due to the dispersive coupling efficiency between the input waveguide and the ring resonator, which is also predict by the coupled m
40、ode theory in time considering the dispersive relation. The near-zero transmission in the drop port at resonant wavelengths and large transmission in the drop port at off-resonance wavelengths are observed due to the near zero and over coupling coefficient, respectively, which cause large degradatio
41、n of the extinction ratio and finesse. The coupling dispersion of the optical filter can be predicted by the coupled mode theory analysis of two coupling straight waveguides with the same coupling length as the filter. In addition, an asymmetrical coupling structure is proposed to compress the dispe
42、rsive coupling phenomenon. In a racetrack filter with the radius of the ring 2 m, the length of the straight part of the racetrack 3.5 m, refractive index 3.2, the widths of the resonator 0.2 m and the air gap 0.2 m, the extinction ratio and the finesse at width of input/output waveguide W = 0.24m g
43、et 14dB and 8 times improvements respectively relative to the case as W = .2 m. Traveling-wave filtering response is demonstrated in an isolate deformed square resonator filter with circular or cut cornersm, the drop/add and drop/through ratio increase 15 and 14 dB respectively. Furthermore, the fre
44、e spectra region increases to more than 100nm. The mode coupling between two degenerate modes with inverse symmetry properties in the deformed SR is found to be the reason of the traveling-wave filtering response. The optimized deformation parameters for an add-drop filter can be accurately predicte
45、d as the overlapping point of the two coupling modes in an isolated deformed square cavity, which releases much computation burden of the filters simulation. More than 80% power dropping can be obtained in a deformed square cavity filter with side length 3.01 m. The free spectra region is decided by
46、 the mode spacing between modes with the sum of mode indexes differing by 1.Programs used to analyze the energy band for 2D and 3D photonic crystals, the localized states in photonic crystal cavity, photonic crystal waveguide and photonic crystal fiber are developed based on FDTD technique and Pad approximation. The program is accurate and efficient even at quality factor as high as 1011, and the calculating time and memory are deduced by several orders compared to the FFT method.Key words: Optical microcavities, microcavity filters, photonic crystals, semiconductor lasers, FDTD