硅基波导光栅耦合器与波导传输损耗的研究

对硅(Si)基波导光栅耦合器的设计与耦合性能进 行了研究。采用本征模展开法对光栅耦合器进行设计与 优化,通过实验测量了光栅的耦合性能,并对均匀光栅、自聚焦光栅和反射光栅等3种光栅 耦合器的耦合 性能进行了比较,耦合效率分别达到了达到47.86、56. 36和48.98%,自聚焦光栅可以有效改善光纤到 光纤的传输效果,耦合效率提高了8.5%。通过实验测量了基于耦合光 栅技术的Si基条形波导和槽型波导的 传输损耗,结果显示,条形波导和槽型波导的传输损耗分别为2.34d B/cm和6.31dB/mm。     

波导光栅耦合器

介绍了近几年国外波导光栅耦合器的研究和应用情况，重点介绍了光栅参数和波导结构对波导光栅耦耦器输入耦合效率的影响以及光栅耦合器在光盘读出头、传感器、光 谱分析等方面的应用。     

聚合物波导光栅耦合器的衍射场仿真

为了实现横截面尺寸为50 m50 m的聚硅氧烷聚合物光波导的耦合转向问题,设计了一种表面覆盖高折射率包层的多层蚀刻光栅耦合器。首先,分析了影响聚合物波导光栅耦合器耦合效率的结构因素;然后,采用在光栅表面蚀刻高折射率层的方法,提高了聚合物波导光栅耦合器的耦合效率;接着,对不同的周期（范围:100~4 000 nm）和不同的蚀刻深度（范围:0~50 000 nm）进行排列组合,形成不同的光栅结构,基于时域有限差分法编写程序,遍历所有情况,得到不同光栅结构下的光场情况以及其耦合效率,找到使耦合效率最大的周期以及蚀刻深度。最后,设计了多层蚀刻的光栅耦合器,进一步提高耦合效率。当蚀刻深度为5 000 nm,光栅周期为2 600 nm时,带高折射率层的聚硅氧烷聚合物光波导均匀光栅耦合器的耦合效率达到最大,为17.2%。采用多层蚀刻的方式,对结构进行优化,其耦合效率能达到37.4%。为聚硅氧烷聚合物光波导在光互连中的实际应用提供了理论依据。     

基于表面等离子波耦合的流体波导光栅耦合器

提出了一种由金属光栅和流体光波导结构组成的,基于表面等离子波耦合的光栅耦合器。利用光栅的衍射效应,将金属光栅与介质分界面之间产生的表面等离子波耦合到流体光波导中,并且能够沿着流体光波导稳定地向前传播。通过采用基于有限时域差分算法的FDTD Solutions软件对光栅耦合器进行了参数优化及特性分析,通过优化使该结构在650 nm波长下的耦合效率达到56%。此外,由于该结构对TE偏振光和TM偏振光的选择比达到70∶1,因此具有偏振器的功能。同时由于TE偏振光耦合频谱的频带宽度仅为20 nm,该结构还具有窄带滤波的作用。此外,还研究了光栅结构参数、入射角以及流体折射率对耦合频谱的影响。     

基于光栅侧面耦合的宽光带集光技术

利用光栅侧面耦合技术多为单波长或窄带光耦合,用于光纤激光器泵浦、光波导集成等领域,而用于可见光宽带耦合的研究很少。通过在波导上集成亚波长衍射光栅结构,可以引导太阳光在波导的侧面进行出光汇集,作为一种新型的太阳能集光器结构。利用时域有限差分算法软件(FDTD)对光栅结构进行仿真,以获得最大衍射效率的光栅结构参数,并对不同入射角度下的衍射耦合效率进行了分析。结果显示,在宽波段的光谱范围内,以上光栅结构均达到较好的衍射效率,其中闪耀光栅衍射效率最大,其衍射效率可达48.8%。这种利用亚波长衍射光栅结构的小型集光器有望应用在有关太阳能能量的收集应用中,例如照明、太阳能电池等。     

掺半导体玻璃波导光栅耦合器及其功率限制作用

本文报导了在掺半导体玻璃波导上用离子刻蚀的方法制备出了表面刻蚀光栅耦合器。观察到了光栅耦合器的耦合效率随着输入激光功率增加而下降的功率限制作用。     

掺半导体玻璃波导光栅耦合器及其功率限制作用

本文报导了在掺半导体玻璃波导上用离子刻蚀的方法制备出了表面刻蚀光栅耦合器。观察到了光栅耦合器的耦合效率随着输入激光功率增加而下降的功率限制作用。     

非对称十字孔双脊波导定向耦合器的设计

借鉴波导定向耦合器的设计原理,采用双脊波导的形式（本文采用标准双脊波导WRD650型号）设计大功率宽频带定向耦合器。由于双脊波导相比于矩形波导,最低模式的截止频率更低,单模工作的频带更宽,特性阻抗更低,所以采用双脊波导的形式比矩形波导在带宽方面更有优势。波导耦合器耦合方式有很多种,最常用的有小孔耦合和缝隙耦合,本文采用非对称十字孔耦合的方式,并与等孔径分布和切比雪夫分布的圆孔耦合比较来确定非对称十字孔耦合方式,在耦合平坦度、方向性方面有更好的改进。利用电磁仿真软件进行仿真对比其结果,通过一些具体措施改善双脊波导定向耦合器的性能,使定向耦合器的各种设计指标达到要求。     

锗酸铋棱镜耦合器

目前研究涉及集成光学领域的课题时,都需要把激光束耦合到光波导中,或把制导光束从波导中耦合出来,耦合的方法分为两类:(1)把光束聚焦射到光波导的横截面的横向耦合器,包括“直接”和“迎面”〔图1〕;(2)光束倾斜入射到波导上的纵向耦合器、包括棱镜、光栅、和劈形波导耦台器,通常波导只有微米的数量级.横向耦合器要求光束高度聚焦和仔细对准.截面上波导部分难于加工到很高的光洁度,有时虽利用晶体的解理面,仍要引起过量的光散射、劈形耦合器作为输入耦合器时,效率也只有20—40%,这两种方法只有找不到高折射率的棱镜材料才被迫使用,只要在整个耦合区域     

多孔耦合型太赫兹波导定向耦合器的设计

设计了一种结构紧凑、工作频带较宽、耦合平稳、高方向性的十字形多孔耦合的太赫兹波导定向耦合器。基于多孔耦合原理,利用HFSS软件对太赫兹波导定向耦合器进行了模型仿真和结构优化。仿真结果表明:在325~475 GHz带宽范围内,该多孔耦合太赫兹波导定向耦合器耦合度达到7.50.8 dB,隔离度达到30 dB,即方向性优于20 dB,各端口回波损耗小于-20 dB。通过对该波导定向耦合器进行高温高压模拟仿真,确定了使用负性光刻胶SU-8作为结构材料的可行性,提出应用MEMS工艺在硅衬底上进行加工,将牺牲层工艺应用到波导腔结构的制作中。利用光刻在直通波导和耦合波导公共宽壁上形成的十字形等间距排列耦合孔结构,可以实现较宽的带宽和良好的耦合平坦度。该方法提高了耦合孔尺寸和位置的精度,减小了反射损耗,为太赫兹波导结构的加工提供了新思路。     

Improved light coupling efficiency of organic light- emitting diode and polymer optical waveguide integrated device by grating coupler

In this work, the light coupling efficiency of organic light-emitting diode (OLED) and polymer optical waveguide integrated device was improved by the grating coupler. To maximize light coupling efficiency, the grating coupler was optimized by finite-difference time-domain (FDTD) method. Based on the simulation results, the grating coupler was fabricated via laser interference lithography process and an OLED was integrated on the surface of it. Comparing the integrated devices without and with grating coupler, light coupling efficiency of the grating-based integrated device was improved by about 5%. The proposed integrated device has the potential application for low-cost and flexible monolithic optical sensors.     

Determination of diffraction efficiency for a second-ordercorrugated waveguide

The diffraction from a second-order corrugated waveguide is analyzed to determine its efficiency as an element to redirect a guided wave. Using a rectangular grating, the efficiency is evaluated in an approximate closed form. The dependence upon grating thickness, waveguide thickness, and wavelength are investigated and the results indicate usefulness as a simulation tool for photonic integrated circuits     

Wavelength-selective coupling between vertically integratedthin-film waveguides via supermode by a pair of grating couplers

Grating coupling between vertically integrated waveguides via supermode was discussed and demonstrated. Two thin-film waveguides with grating couplers were stacked on a substrate. A guided wave in one waveguide is converted by a grating coupler to a supermode propagating contradirectionally, and then converted by another grating coupler to a guided wave in the other waveguide. The coupling shows high wavelength selectivity, and the wavelength-division add/drop multiplexing function can be combined. A demonstrator was designed and fabricated. Theoretically predicted coupling efficiency was almost 100% with wavelength selectivity of 2 nm, while the experimentally obtained value was 40% in the efficiency and 1 nm in the selectivity     

Focusing Polarization Diversity Grating Couplers in Silicon-on-Insulator

We report on compact focusing polarization diversity grating couplers in silicon-on-insulator, which can be used to overcome the polarization dependence of nanophotonic integrated circuits. The minimum fiber-to-fiber polarization dependent loss is 0.4 dB and the focusing grating couplers are as performant as standard 2-D-grating couplers without focusing. In addition, the focusing property of the gratings results in an 8-fold length reduction of the coupling structure as compared to standard nonfocusing 2-D-grating versions.     

硅基光栅耦合封装结构的优化设计

为了提高硅基光栅耦合封装结构的耦合效率、增大容差范围,对光栅耦合的结构特性进行了理论分析,并采用时域有限差分法完成了仿真验证,在不改变光栅参量的基础上,对光栅耦合封装结构进行了改进,仿真建立了一款光栅上方和光纤端面分别增加透镜的优化结构,研究了影响耦合效率的因素。结果表明,增加透镜后,耦合效率有所增加,角度容差和带宽都有一定的优化;在衬底增加反射镜后,对波长1550nm的光耦合效率提高至73.809%。该研究结果可为光栅耦合的封装结构设计提供参考依据。     

Etched Waveguide Grating Variable 1 $,times,$2 Splitter/Combiner and Waveguide Coupler

We propose and test a silicon waveguide grating which serves dual functions: as a 1$,times,$ 2 variable integrated beam splitter/combiner and as an out-of plane diffractive element for coupling light between a single-mode optical fiber and a 500-nm-wide silicon-on-insulator waveguide. An integrated Mach–Zehnder interferometer made with this novel functional element had over 20-dB extinction ratio. The splitting ratio can be tuned by changing the launch position of the optical fiber. The grating coupler had over 36% coupling efficiency and a 1-dB spectral bandwidth of 37 nm.      

量子阱红外探测器双面金属光栅设计优化

提出了一种增强量子阱红外探测器耦合效率的双面金属光栅结构。采用三维时域有限差分算法（3D-FDTD）对GaAs/AlGaAs 量子阱红外探测器双面结构金属光栅进行了仿真分析。通过对比不同周期、占空比、金属层厚度结构参数下探测器的电场分布及相对耦合效率,确定了4.8 m 探测器优化的双面金属光栅结构。与顶部和底部单层金属光栅结构比较,双面金属光栅结构探测器相对耦合效率提高到3 倍以上。探测器相对耦合效率随光栅周期变化的双峰曲线特性体现了双面金属光栅结构在双色量子阱红外探测器光耦合方面的潜力。同时该结构还可以应用于单色、双色及多色量子阱焦平面红外探测器。     

倾斜耦合的光栅耦合器研究进展

近年来,片上光子集成技术备受关注并飞速发展,但在光纤与芯片、芯片与芯片上实现高效、高可靠性的光耦合仍是难题。光栅因其制作简单,位置灵活,对准容差大及可实现片上测试等一系列优点而备受研究者的关注。目前在绝缘体上硅(SOI)平台和绝缘体上铌酸锂(LNOI)平台上已开发出大量的光栅耦合器件,并获得较高的耦合效率和大带宽。该文主要介绍光栅耦合器的工作原理和主要性能指标,阐述了均匀光栅、倾斜光栅、闪耀光栅和切趾光栅耦合的特点及现阶段进展,并对具有代表性的一维光栅性能指标进行了比较。结果表明,分布式布喇格反射镜和金属反射镜可有效地提升光栅耦合效率。此外,该文还介绍了基于 LNOI平台的几种光栅耦合器, 其可帮助研究者们梳理光栅耦合器的发展历程、研究现状及各耦合器的特点,为未来研究提供一定的参考。     

3-Dimensionally Integrated Planar Optics for 100 Gb/s Optical Packet Address Detection

We propose a novel planar optical interconnection scheme for 100 Gb/s optical packet address detection, which consists of waveguide grating couplers and a diffractive microlens integrated on a glass substrate 3-dimensionally. Length and duty cycle of the grating couplers have been determined on the bases of the ray-optic propagation-mode analysis in a slab waveguide and of the rigorous coupled-wave diffraction analysis for out-coupled radiation-modes. The 3-dimensionally integrated planar optics makes it possible to connect each address bit-signals of TE₀-waveguide mode to the detector with a power uniformity of 6.4 % and a total coupling efficiency of 72.3 %.