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1.
厉以宇  顾培夫  李明宇 《物理学报》2005,54(8):3889-3893
基于自动复形技术,在148—152μm的近红外波段设计了可以实现全角度偏振分束(TM模透过,TE模反射)的波状膜层二维光子晶体结构.从能带角度解释了全角度偏振分束的原理.波状膜层倾角θ和a-Si单层膜厚T分别可以在38°—49°和014—015μm的范围内变动,不影响全角度的偏振特性.对波状膜层进行了变形,针对波长128—1 31μm设计了宽角度偏振分束的箭羽型二维光子晶体结构.对比两种结构的能带,阐明了二 维光子晶体偏振分束器光线入射角范围的拓宽与能带结构变化的关系.能带计算全部采用平 面波展开算法. 关键词: 偏振分束 平面波展开 完全禁带  相似文献   

2.
基于自准直效应的光子晶体异质结偏振分束器   总被引:1,自引:0,他引:1       下载免费PDF全文
左依凡  李培丽  栾开智  王磊 《物理学报》2018,67(3):34204-034204
基于光子晶体的自准直效应和禁带特性,提出了一种具有非正交异质结结构的光子晶体偏振分束器.无需引入缺陷或波导,可使光波在该结构中准直无发散地传输并实现分束功能,对制造工艺的要求大大降低.利用Rsoft软件,结合平面波展开法和二维时域有限差分法,对提出的偏振分束器进行了仿真研究.结果表明,该偏振分束器在一个较大的频率范围f=0.275—0.285(a/λ)内可实现横电(TE)和横磁(TM)模的大角度偏振分离,TE和TM模的透过率均在88%以上,偏振消光比分别大于26.57 dB和17.50 dB.该结构可应用到太赫兹波段的传输系统中,a=26μm,尺寸大小为572μm×546μm,在91—95μm波长范围内可实现TE和TM模的分离.利用该结构可设计用于光通信系统(n=3.48)的偏振分束器,a=426.25 nm,结构仅为9.38μm×8.95μm.本方案结构简单,易于集成,有望在集成光路的发展中发挥重要作用.  相似文献   

3.
光控二维光子晶体光开关   总被引:1,自引:0,他引:1  
谭春华  黄旭光 《应用光学》2008,29(3):452-457
提出了一种调节液晶光子晶体光子带隙的方法。二维三角介质柱形光子晶体位于2块熔凝石英片之间,在介质柱之间填充各向同性排列的液晶,受偏振紫外光照射后,光诱导液晶分子定向排列,通过光诱导液晶分子取向改变液晶的折射率。数值模拟结果表明:通过外界光场控制所填充的向列相液晶分子的方向可以对这种二维三角形介质柱光子晶体的禁带结构进行调节。该可调光子晶体可控制波导中TM模和TE模的选择性传输,因而可应用于制作全光光开关。  相似文献   

4.
一种衍生于三角晶格的二维光子晶体   总被引:1,自引:1,他引:0  
通过在二维三角晶格中引入三个完全相同的介质圆柱构成了一种全新结构的光子晶体,并对其光子能带进行了频域计算.借助数值方法分析了填充率对光子能带的影响,结果表明,在一定填充率下,这种二维光子晶体对于E偏振和H偏振都存在很宽的带隙,而且还可以获得一个窄完全带隙.  相似文献   

5.
从能带结构和等频面两方面完整阐述了利用光子晶体实现全角度偏振分束的条件,分析等频面目的在于确保波矢的切向分量保持连续,采用时域有限差分(FDTD)方法模拟了高斯光束在波状膜层中的传播过程,通过对比TE模与TM模在0°—89°不同入射角情况下的振幅透射系数,理论上验证了波状膜层的全角度偏振分束效应. 关键词: 光子晶体 偏振分束 等频面  相似文献   

6.
一种新型光子晶体波导定向耦合型超微偏振光分束器   总被引:3,自引:1,他引:2  
将两个二维空气孔光子晶体波导平行放置,两波导之间由三排空气孔相隔,构成一个定向耦合器.数值分析了TE(磁场平行于空气孔)和TM(电场平行于空气孔)偏振态光波在该定向耦合器中的传播行为.结果表明,减小耦合区两波导间的一排介质柱的半径,TE模的耦合长度减小,而TM模的耦合长度不变.基于此结构,设计了超微偏振光分束器,整个器件的尺寸为10.1μm,与已报道的24.2μm的结果相比,该器件具有更小的器件尺寸和更高的输出效率.  相似文献   

7.
二维正方晶格光子晶体禁带特性   总被引:3,自引:3,他引:0  
张杰 《光谱实验室》2012,29(2):1192-1194
基于平面波展开法,以碳化硅构成二维正方晶格光子晶体,数值模拟了TE模、TM模二维光子晶体的禁带特性,结果表明,TE模更容易形成光子禁带。同时设计了以碳化硅构成二维正方晶格光子晶体波导,数值模拟了TE模、TM模波导的传输特性和禁带特性,结果表明,TE模构成的波导电磁波能够较好的传播,它们的光子禁带都没有出现。研究结论为光子晶体波导器件的开发提供参考。  相似文献   

8.
设计了Y型和回型二维光子晶体波导,基于时域有限差分法模拟了传输特性,并得出Y型结构对应的TE模、TM模的带隙结构。为此可以根据具体情况设计满足不同要求的波导结构。  相似文献   

9.
利用有限时域差分法(FDTD)进行数值模拟,在二维光子晶体中实现了电磁波两种偏振态的自准直——全光自准直(full-light-self-collimation).研究表明,通过对光子晶体的结构做适当的调整,可以在较宽频率范围内实现横电波(TE波)和横磁波(TM波)沿着相同方向传播,同时保持较强的能流强度.全光自准直可以显著提高光源利用率和光波导的传播效率,在高密度集成光路中有非常重要的用途. 关键词: 光子晶体 偏振 自准直  相似文献   

10.
并联谐振腔光子晶体单通道侧面耦合波导   总被引:5,自引:2,他引:3  
崔乃迪  梁静秋  梁中翥  王维彪 《光学学报》2012,32(2):223001-300
分析了多光子晶体谐振腔的并联耦合模理论,并根据该理论设计了单通道光子晶体侧面耦合波导以实现光子晶体器件与光源间的高效耦合。理论研究表明并联谐振腔的耦合效率与谐振腔数量、间距以及品质因子相关。经优化耦合面积和耦合效率,最终选择了5个谐振腔并联作为单通道侧面耦合波导的耦合部分。通过设置谐振腔间距改变其对称性,从而实现侧面耦合波导的单通道传播。在1.55μm工作波长下,单通道侧面耦合波导的耦合效率可达94.49%。  相似文献   

11.
麻健勇  许程  强颖怀  朱亚波 《中国物理 B》2011,20(10):104209-104209
A broadband non-polarizing beam splitter (NPBS) operating in the telecommunication C+L band is designed by using the guided mode resonance effect of periodic silicon-on-insulator (SOI) elements. It is shown that this double layer SOI structure can provide ~50/50 beam ratio with the maximum divergences between reflection and transmission being less than 8% over the spectrum of 1.4 μm~1.7 μm and 1% in the telecommunication band for both TE and TM polarizations. The physical basis of this broadband non-polarizing property is on the simultaneous excitation of the TE and TM strong modulation waveguide modes near the designed spectrum band. Meanwhile, the electric field distributions for both TE and TM polarizations verify the resonant origin of spectrum in the periodic SOI structure. Furthermore, it is demonstrated with our calculations that the beam splitter proposed here is tolerant to the deviations of incident angle and structure parameters, which make it very easy to be fabricated with current IC technology.  相似文献   

12.
蔡鑫伦  黄德修  张新亮 《物理学报》2007,56(4):2268-2274
采用精确、严格的全矢量模式匹配法,计算了三维脊型弯曲波导和条形弯曲波导的本征模式,分析了模式折射率和辐射损耗随弯曲半径的变化关系.计算结果与已报道的有限差分法的结果符合很好.对文献中已报道但没有深入分析的现象给出了合理的解释.半径为50和12 μm的条形波导的计算结果表明:当波导的弯曲半径减小时,发生在分界面处的TE-TM模耦合会显著增强,这将导致弯曲波导中的模式不再是传统意义上的准TE模和准TM模,而是混合模.随着半径的减小,混合模的横向分量之间的差异会减小,当两个横向分量达到近似相等的强度时,波导的偏振相关性将会大大减小. 关键词: 导波光学 全矢量模式匹配法 微环谐振腔 光波导理论  相似文献   

13.
Mid-infrared photonics in silicon needs low-loss integrated waveguides. While monocrystalline germanium waveguides on silicon have been proposed, experimental realization has not been reported. Here we demonstrate a germanium strip waveguide on a silicon substrate. It is designed for single mode transmission of light in transverse magnetic (TM) polarization generated from quantum cascade lasers at a wavelength of 5.8 μm. The propagation losses were measured with the Fabry-Perot resonance method. The lowest achieved propagation loss is 2.5 dB/cm, while the bending loss is measured to be 0.12 dB for a 90° bend with a radius of 115 μm.  相似文献   

14.
Silicon waveguide polarizers offer a simple yet robust approach to address the polarization‐dependent issue of silicon‐based optical components, and hence have found numerous applications in silicon photonics. However, the available silicon waveguide polarizers suffer from the issue of large device footprint, high insertion loss (IL), and/or fabrication complexities. Here, a silicon waveguide transverse magnetic (TM)‐pass polarizer is constructed by coating a silicon waveguide with an ultra‐thin plasmonic metasurface structure that is capable of guiding slow surface wave (SW) mode. The transverse electric (TE) waveguide mode can be converted into SW mode with the involvement of metasurfaces, and hence is intrinsically absorbed and forbidden to pass, while the TM waveguide mode can be well guided due to little influence. A typical metasurface polarizer with an ultra‐short length of 2.4 µm enables the IL of 28.16 dB for the TE mode, and that of 0.53 dB for the TM mode at 1550 nm. Multiple‐band TM‐pass polarizers can be obtained by cascading two or more different metasurface‐coated silicon waveguides along the propagation direction, and a dual‐band TM‐pass polarizer is demonstrated with the IL being of 19.21 and 29.09 dB for the TE mode at 1310 and 1550 nm, respectively.  相似文献   

15.
李伟军  向东 《发光学报》2013,34(12):1657-1661
运用时域有限差分(FDTD)方法数值研究了一种亚波长之字形金属-绝缘体-金属(MIM)等离子波导结构的传输属性。之字形波导在连续两个拐角可向外延伸出1~4个短切口。每个切口独立构成一个谐振腔,谐振波长近似与切口深度成线性正比,而与切口方向无关。当任意一个切口满足谐振条件时,该波导结构在对应波长的透射率均趋近于0。随着同深度切口数目的增加,禁带波长区域逐渐展宽,形成一个良好的宽带滤波器。  相似文献   

16.
 利用有限元方法求解:S-参数矩阵,研究了过模慢波结构对圆波导TM01,TM02模的反射特性,分析了在慢波结构末端加入谐振腔后,由于两端口的不对称性而造成的对反射特性影响。结果表明,在TM01的π模频率附近,慢波结构和谐振腔组成的系统对无谐振腔一侧端口入射TM01模的反射增大,而对有谐振腔一侧端口入射TM01模的反射减小。根据计算结果,解释了普通多波切伦柯夫振荡器所用慢波结构周期数较多的原因,说明了在多波切伦柯夫振荡器中引入谐振腔后,不但可以减少所用慢波结构周期数,而且有利于提高微波输出效率。  相似文献   

17.
The conditions for maximum longitudinal electric field of a TM mode at the surface of a step index slab waveguide, and the value of this maximum are given in a normalized analytical form. They are applied to a grating coupling structure corresponding to a resonant laser mirror or to optical interconnects involving a normally incident free space wave and a singlemode slab waveguide.  相似文献   

18.
In this work, we demonstrate surface plasmon resonance properties and field confinement under a strong interaction between a waveguide and graphene nanoribbons (GNRs), obtained by coupling with a nanocavity. The optical transmission of a waveguide–cavity–graphene structure is investigated by finite-difference time-domain simulations and coupled-mode theory. The resonant frequency and intensity of the GNR resonant modes can be precisely controlled by tuning the Fermi energy and carrier mobility of the graphene, respectively. Moreover, the refractive index of the cavity core, the susceptibility χ(3) and the intensity of incident light have little effect on the GNR resonant modes, but have good tunability to the cavity resonant mode. The cavity length also has good tunability to the resonant mode of cavity. A strong interaction between the GNR resonant modes and the cavity resonant mode appears at a cavity length of L1 = 350 nm. We also demonstrate the slow-light effect of this waveguide–cavity–graphene structure and an optical bistability effect in the plasmonic cavity mode by changing the intensity of the incident light. This waveguide–cavity–graphene structure can potentially be utilised to enhance optical confinement in graphene nano-integrated circuits for optical processing applications.  相似文献   

19.
A novel overmoded slow-wave high-power microwave (HPM) Generator   总被引:3,自引:0,他引:3  
We present the design and experimental results of a novel overmoded slow-wave high-power microwave (HPM) generator that is featured by its compactness, low-operation magnetic field, and potentially high power and high efficiency. The device includes two slow-wave structure (SWS) sections, a resonant cavity, and a tapered waveguide. The resonant cavity was well designed and was used to achieve the axial mode selection and to decrease the length of the SWS sections. The radial mode selection is achieved using the property of "surface wave" of the device to excite the TM/sub 01/ mode while making the higher TM/sub 0n/ modes unexcited. The physical mechanisms of axial and radial mode selections ensure that the microwave is produced with a single mode and a narrow band. The feasibility of low magnetic field operation is also investigated based on the characteristics of the overmoded slow-wave devices. Experiments were carried out at the Spark-2 accelerator. At diode voltage of 474 kV, beam current of 5.2 kA, and guiding magnetic field strength of 0.6 T, a microwave was generated with power of 510 MW, mode of TM/sub 01/, and frequency of 9.54 GHz. The relative half width of the frequency spectrum is /spl Delta/f/f= 0.6%, and the beam-to-microwave efficiency is about 21% in our experiment.  相似文献   

20.
Xiao Z  Luan F  Liow TY  Zhang J  Shum P 《Optics letters》2012,37(4):530-532
In this Letter, we propose general optimization methods to design broadband high-efficiency grating couplers for planar waveguides. We attribute the coupling bandwidth to the mismatch of effective indices between the diffracted beam and the actual grating structure around the operation wavelength for fiber to waveguide excitation. The coupling bandwidth formula is deduced. A simple parameter-separate optimization procedure is proposed for general layered grating couplers for high coupling efficiency. Using our principle, we optimized a grating coupler for a horizontal slot waveguide operating at wavelength 1.55 μm for TM polarization. The grating coupler has 1 dB bandwidth of 60 nm and coupling efficiency of 65% with incident light from single-mode optical fiber (SMF) at 8°.  相似文献   

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