【作者】 时尧成；

【导师】 何赛灵；

【作者基本信息】 浙江大学 ， 光学工程， 2008， 博士

【摘要】 建立在平面光波导技术之上的光器件,具有成本低、体积小、便于批量生产、稳定性好及易于与其它器件集成等优点。目前,平面光波导集成光学元件已在通信、军事、电力、天文、传感等应用领域中发挥着重要作用。本文以基于平面光波导技术的耦合/干涉型光器件作为研究对象,在平面光波导的基本理论及设计方法的基础上,提出并设计了一些新型的器件结构,利用平面光波导工艺制作了一些器件并测试了其性能。首先对平面光波导及其器件的模拟设计方法进行了研究。分析了用于求解光波导模场的解析方法,对传统等效折射率方法进行了改进,从波动方程出发,通过严格的数学推导,得到了一维等效折射率分布的表达式,这种方法具有比传统等效折射率方法更高的精度,而且不受波导截止条件的限制,并适用于任意的折射率分布结构。对平面光波导器件设计中常用的数值方法包括有限差分法,束传播法,时域有限差分等进行了总结,给出了各种方法的基本原理,具体的求解步骤等,利用这些数值方法可以得到光波导的模场分布,光波在器件中的传播特性,器件的频谱特性等等。然后分析了多模干涉耦合器垂直方向多模对器件的性能的影响,通过对输入输出波导进行taper设计,可以减小垂直方向多模的激发,使得功分器的通道均匀性,损耗等性能都得到改善。提出了深刻蚀SiO₂光波导结构,使得SiO₂波导在小的弯曲半径下也能有比较小的弯曲损耗,分析了基于这种深刻蚀SiO₂波导的多模干涉耦合功分器,与基于传统SiO₂波导的多模干涉耦合功分器相比不仅具有较小的尺寸,同时性能也有很大的提高。我们还提出了几种新的基于平面光波导的器件的实现方法。通过调整三明治波导中间层Si_xN_y的折射率以及多模波导的尺寸,成功实现了偏振不敏感的1310/1550nm波分（解）复用器。通过在多模干涉耦合器的多模区引入光子晶体结构,利用光子晶体的偏振敏感特性（即在某个波段,对一个偏振反射,而对另外一个偏振则透射）,实现了带宽很宽,尺寸超小的偏振分束器。利用光子晶体波导方向耦合器的解耦合特性,通过方向耦合器的级联,设计了单纤三向器件,模拟结果显示,这种单纤三向器件具有尺寸小,带宽较大的特点。我们还总结了平面光波导器件的制作工艺流程,包括光刻技术（电子束曝光）,反应离子刻蚀（RIE）,电感耦合型等离子刻蚀（ICP）等。通过优化气体配比,反应功率等条件,得到了一组能提供小的表面粗糙度,高的垂直度的ICP工艺配方,同时还研究了ICP刻蚀中的迟滞效应,并利用这种效应制作了尺寸超小的方向耦合器。制作了光子晶体W3波导,光子晶体波导腔,利用End-Fire方法对其特性进行了测试,分析和讨论。最后还研究了干法刻蚀工艺中引入的损伤对光子晶体有源区的载流子寿命的影响,为制作光子晶体光开关,激光器奠定了基础。更多还原

【Abstract】 The optical devices based on planar lightwave circuit（PLC）technology have the advantages of small size,high reliability,possibility for large scale production,and potential integration with the photonic and electronic devices.These devices are widely employed in optical telecommunications,sensing,data storage,imaging,and signal processing.This thesis is mainly devoted to study some PLC based devices, including power splitters,demultiplexer,triplexer and polarization splitter.First,the basic principle of the waveguide and the simulation methods for PLC devices are introduced.A novel effective index method is introduced to reduce a two-dimensional structure to a one-dimensional one.This method can be implemented for arbitrarily shaped waveguides.An explicit formula is obtained for the effective refractive index profile,which is determined by the modal filed and the cross-sectional refractive index of the original structure.Some numerical methods, including finite-difference mode solver,beam propagation method,finite-difference time-domain method are introduced to analysis the mode profile of the waveguides, and the propagation properties of light in devices.Multimode effects in the vertical direction which will degrade the self-imaging quality of a Multimode Interference（MMI）coupler are analyzed.Taper structures are introduced at the junction between input/output waveguides and multimode region to suppress the excitation of the undesired vertical modes and low insertion loss （0.101dB）,small non-uniformity（0.102dB）are achieved.Deeply-etched SiO₂ ridge waveguides are introduced to a MMI power splitter.The strong confinement in the lateral direction of the deeply-etched SiO₂ ridge waveguides improves the quality of self-images in the MMI section.Good performances such as a low insertion loss,small non-uniformity are achieved for a 1×4 MMI power splitter and the total device size of the present MMI power splitter is reduced to about 1/16 of that based on SiO₂ buried waveguides. Some kinds of PLC based devices were studied and optimized.A polarization insensitive dual wavelength demultiplexer based on sandwiched multimode interference waveguides is presented.Firstly,polarization insensitive multimode waveguides are achieved by choosing a suitable refractive index of the SiN_x middle region.By adjusting the width and length of the multimode region,the wavelengths of 1310 nm and 1550 nm are separated successfully.Three-dimensional beam propagation method is used to simulate the whole structure.A low insertion loss and a broad bandwidth can be achieved at 1310 and 1550nm bands for both polarizations simultaneously.Two stages of directional couplers based on photonic crystal waveguides are cascaded to form an ultracompact triplexer.The special decoupling property of the PCW-based directional coupler is utilized for the design.A taper coupling region and an additional directional coupler are introduced to achieve high extinction ratios and reduce the crosstalk respectively.The total size of the present triplexer is only 50μm×20μm,and the good performance is verified with FDTD simulation.A novel polarization beam splitter is realized by combining MMI coupler and a photonic crystal.The PC structure is introduced in the multimode section of the MMI coupler working as a polarization sensitive reflector.One polarization is reflected and the other one transmits through the PC structure.The size of the proposed PBS is rather small since the length of the MMI region is no longer needed to be integer multiples of the coupling lengths for both polarizations.Finally,the fabrication procedures including electron beam lithography and etching and end-fire characterization technologies for PLC components are reviewed. Some devices are fabricated based on semiconductor clean room facilities to verify the design.更多还原