Temperature Dependence of Characteristics for Multimode Interference Based 3—dB Coupler in SOI

The temperature dependence of characteristics for multimode interference (MMI) based 3-dB coupler in silicon-on-insulator is analyzed, which originates from the relatively high thermo-optic coefficient of silicon.For restricted interference 3-dB MMI coupler,the output power uniformity is ideally 0 at room temperature and becomes 0.32 dB when temperature rises up to 550 K.For symmetric interference 3-dB MMI coupler,the power uniformity keeps ideally 0 due to its intrinsic symmetric interference mechanism.With the temperature rising,the excess loss of the both devices increases.The performance deterioration due to temperature variety is more obvious to restricted interference MMI3-dB coupler,comparing with that of symmetric interference MMI3-dB coupler.     

一种紧缩型的SOI3- d B多模干涉耦合器

采用线锥形结构 ,在 silicon- on- insulator(SOI)材料上设计并实现了一种新的紧缩型 3- d B多模干涉耦合器(MMI) .与普通的矩形结构 3- d B MMI耦合器相比 ,该器件长度减少了 4 0 % .耦合器输出均衡度为 1.3d B,过剩损耗为 2 .5 d B.     

基于SOI的2×2 MMI耦合器的设计

设计了一种可用于阵列波导光栅(AWG)解调集成微系统的绝缘体上硅(SOI)基2×2多模干涉(MMI)耦合器,用光束传播法(BPM)对MMI耦合器进行了模拟。耦合器输入/输出波导采用倒锥形,多模干涉区尺寸为6μm×57μm。在TE偏振中心波长为1.55μm时,器件附加损耗为0.46dB,不均匀性为0.06dB。在1.49～1.59μm波长范围内耦合器的附加损耗小于1.55dB。仿真结果表明所设计的2×2MMI耦合器体积小、附加损耗低、波长响应范围宽、分光均匀,符合片上集成系统的要求。     

三分量加速度地震检波器中3-dB耦合器设计

三分量加速度地震检波器检测加速度的核心部件是由2个3-dB耦合器级联而成的双M-Z干涉仪,3-dB耦合器的设计对三分量加速度地震检波器的检测精度尤为重要。介绍了三分量加速度地震检波器的结构和工作原理,导模之间的同向耦合理论。设置了3-dB耦合器波导的结构和计算参数。采用MATLAB对3-dB耦合器的输出功率进行仿真,仿...     

高均匀性1×4多模干涉耦合器的研究与设计

针对多输出端口输出光功率的不均匀性问题,文章设计了一种基于绝缘体上硅(SOI)的1×4多模干涉(MMI)耦合器,提出了一种优化其均匀性的新方法。耦合器输入/输出端采用锥形波导,为提升MMI耦合器的均匀性,对输出端锥形波导采用不等宽设计,通过优化,四路输出端口均匀性高达0.007 4 dB,而总的插损仅有0.058 dB。依据该方法最终使得输出端波导的传输常数失配,避免了波导之间的串扰,实现了对MMI耦合器输出端口均匀性的提升。     

用于传感的聚合物微谐振环的研制

对一种用于传感的聚合物微谐振环进行了研制.器件为多模耦合器结构,作为微谐振环的输入/输出耦合结构.微谐振环采用跑道形结构.首先分析了器件的原理,给出了器件的优化设计参数.采用紫外光敏材料SU-8和CYTOP作为波导芯层和下包层材料,制作了上述结构的微谐振环器件,并进行了测试.扫描电镜的结果显示,所制备器件的整体形貌比较清晰,波导结构均匀光滑,侧壁陡直度较高.采用截断法测得单模直波导的传输损耗约为2.2 dBcm.对多模耦合器(MMI)结构和弯曲波导的测试表明,MMI结构在较宽的波长范围内实现了接近50:50的功分比,且损耗较低,而纯弯曲波导结构的通光性能良好.测量得到的器件谐振输出光谱表明,器件在主谐振峰处的插入损耗约为38dB,自由光谱区(FSR)约为1.87nm.过数据处理分析得到弯曲波导的传输损耗约为5.2 dB/cm.提出了进一步降低器件损耗、改善器件性能的措施.     

4×4热光SOI波导开关阵列

设计并制作了阻塞型和完全无阻塞型4×4热光SOI(silicon-on-insulator)波导开关阵列。开关单元采用了多模干涉耦合器(MMI)-MZI(Mach-Zehnder interferometer)结构的2×2光开关。阻塞型光开关附加损耗为4.8～5.4dB,串扰为-21.8dB～-14.5dB。完全无阻塞型光开关阵列附加损耗为6.6～9.6dB,串扰为-25.8～-16.8dB。两者的消光比都在17～25dB内变化,开关单元功耗小于230mW。器件的开关时间小于3μs。功耗和开关速度都明显优于SiO2基和聚合物基的开关阵列。     

硅基槽波导级联多模干涉耦合器型偏振分束器

提出了一种基于硅基槽波导的级联多模干涉(MMI)耦合器型偏振分束器,由锥形及矩形结构MMI耦合器构成.级联结构使器件长度无需为两偏振模自镜像长度的公倍数,不仅能有效减小器件尺寸,而且提高设计灵活性.同时,利用槽波导的高双折射特性及MMI耦合器的锥形结构,可进一步缩短器件尺寸.分析结果表明,所提器件能够有效实现偏振束分离,两级MMI工作区总长度仅为42μm,准TE与准TM模的偏振消光比分别为29.8和31.4d B,1.55μm波长下的插入损耗分别为0.395和0.699 d B,偏振消光比大于20 d B时光带宽为43 nm,覆盖整个C波段.最后,详细分析了器件关键参数的制造误差对器件性能的影响.     

一种高隔离度3-dB微带定向耦合器

本文采用接地板开槽的交指耦合悬浮线结构,使3-dB微带定向耦合器的隔离度在1～2GHz频带内优于25dB,耦合线间距0.1mm。既提高了隔离度,又克服了微带定向耦合器紧耦合时工艺要求太高的缺点。全文用谱域技术进行严格分析,用Galerkin法进行数值计算。给出的阻抗曲线和相速曲线为精确设计提供可靠的依据。实验结果与理论分析一致。     

一种超宽带宽边耦合微带定向耦合器

提出了一种新颖的超宽带宽边耦合微带定向耦合器,相比窄边耦合结构,宽边耦合增加了耦合面积,可实现宽频的3 dB紧耦合.同时,为进一步拓展耦合器工作带宽,该文采用渐变耦合结构替代传统的矩形耦合结构.通过HFSS仿真验证,此定向耦合器在2～6 GHz频带内插入损耗小于0.9dB,输入端口回波损耗大于20 dB,端口隔离度大于21 dB.     

Fabrication of 4×4 tapered MMI coupler with large crosssection

MMI coupler with large cross section has low coupling loss between the device and fiber. However, large chip area is required. Recently proposed N×N tapered MMI coupler shows a substantial reduction in device geometry. No such kind of devices with N>2 has yet been realized up to now. The authors have demonstrated a 4×4 parabolically tapered MMI coupler with large cross section that can match the SM fiber in silicon-on-insulator (SOI) technology. The device exhibits a minimum uniformity of 0.36 dB and excess loss of 3.7 dB. It represents a key component for realization of MMI-based silicon integrated optical circuit technology     

Fabrication of 2×2 tapered multimode interference coupler

The authors demonstrate a 3 dB 2×2 parabolically tapered multimode interference (MMI) coupler with a large cross-section and space between the different ports using silicon-on-insulator technology. The device exhibits a uniformity of <0.8 dB and can be used in the realisation of an MMI-based optical switch with a high extinction ratio     

蝶形多模干涉耦合器的数值分析

设计蝶形多模干涉(MMI)耦合器时,需要根据所要求的功率分割比率确定器件的结构参量。作为矩形多模干涉耦合器的特征参量的耦合长度,通过数值分析对称干涉型矩形多模干涉耦合器的成像位置而得到,从而可利用模传输分析(MPA)法的公式设计出蝶形多模干涉耦合器的理论预期结构。使用有限差分波束传输法(FD-BPM)对设计参量进行校正,并且数值算出器件实际实现的功率分割比率。针对基于SOI晶片的设计实例表明,仿真得到的蝶形多模干涉耦合器的长度较理论预期大2～4 μm,实际实现的功率分割比率较理论预期值低且器件形状越偏离矩形,其值相差越大。     

Design of an ultra-compact 3 dB MMI coupler

The design of an ultra-compact SOI-based 1×2 3 dB multimode interference（MMI） coupler is proposed.The symmetric multimode interference structure and deeply-etched parabolically tapered multimode waveguide are used in the device.The length of the device is reduced by about 87% compared with general multimode interference straight couplers.Based on effective index method（EIM） and two dimensional beam propagation method（2D-BPM）,the structure parameters are optimized and the fabrication tolerances are analyzed.The results indicate that the performance of the coupler is deeply affected by the coupler＇s width,etching depth and photolithography alignment error in perpendicular direction.     

Reduced reflections from multimode interference couplers

A 3 dB multimode interference (MMI) coupler optimised for low reflections is presented. The MMI was designed, fabricated and characterised. For comparison, MMIs with non-optimised layout have been included on the same sample. The measurement results show a reduction in reflectivities of more than 10 dB.     

Polarisation-insensitive 980/1550 nm wavelength (de)multiplexerusing MMI couplers

A polarisation-insensitive planar 980/1550 nm wavelength (de)multiplexing coupler based on multimode interference (MMI) effects is presented. The device is useful for integration with rare-earth doped waveguide amplifiers and lasers. The waveguide parameters and, in particular, the coupler width are chosen to optimise the device performance and obtain polarisation-insensitivity     

Compact triangular resonator without direct coupling between two access waveguides

Novel triangular resonators containing active and passive sections have been fabricated and characterised with various multimode-interference (MMI) lengths. The optimum MMI length and width turn out to be 108 and 9 mm, respectively. A free spectral range of approximately 228 GHz is observed near 1558 nm along with an on?off ratio of 9 dB. The proposed triangular resonator has the advantage of removing the direct coupling between the two access waveguides of the MMI coupler.     

Tunable multimode interference coupler

An electrically tunable multimode interference (MMI) coupler/splitter is demonstrated. The device operates by modifying the phase of the multiple self-images that are formed around the midpoint of the MMI structure. This provides a simple way to fine-tune the 50:50 output power split ratio or other arbitrary ratio.