An Ultra-Compact Broadband Polarizing Beam Splitter Utilizing Hybrid Plasmonic Waveguide

Polarizing beam splitter has rather significant applications in polarization diversity circuits and polarization multiplexing systems.In this paper,we present an asymmetric polarizing beam splitter utilizing hybrid plasmonic waveguide.The special hybrid structure with a hybrid waveguide and a dielectric waveguide can limit the energy of TE and TM modes to a different layer.Therefore,we can achieve beam splitting by adjusting the corresponding parameters of the two waveguides.First,we studied the influences of different structure parameters on the real part of the effective mode refractive index of the two waveguides,and obtained a set of parameters that satisfy the condition of strong coupling of TM mode and weak coupling of TE mode.Then,the performance of our proposed polarizing beam splitter is evaluated numerically.The length of the coupling section is only 4.1μm,and the propagation loss of TM and TE modes is 0.0025 d B/μm and 0.0031 d B/μm respectively.Additionally,the extinction ratios of TM and TE modes are 10.62 d B and 12.55 d B,respectively.Particularly,the proposed device has excellent wavelength insensitivity.Over the entire C-band,the fluctuation of the whole normalized output power is less than 0.03.In short,our proposed asymmetric polarizing beam splitter features ultra-compactness,low propagation loss,and broad bandwidth,which would provide promising applications in polarization multiplexing system and polarization diversity circuits relevant to optical interconnection.

A low-threshold nanolaser based on hybrid plasmonic waveguides at the deep subwavelength scale

A novel nanolaser structure based on a hybrid plasmonic waveguide is proposed and investigated. The coupling between the metal nanowire and the high-index semiconductor nanowire with optical gain leads to a strong field enhancement in the air gap region and low propagation loss, which enables the realization of lasing at the deep subwavelength scale.By optimizing the geometric parameters of the structure, a minimal lasing threshold is achieved while maintaining the capacity of ultra-deep subwavelength mode confinement. Compared with the previous coupled nanowire pair based hybrid plasmonic structure, a lower threshold can be obtained with the same geometric parameters. The proposed nanolaser can be integrated into a miniature chip as a nanoscale light source and has the potential to be widely used in optical communication and optical sensing technology.

Hybrid plasmon waveguides with metamaterial substrate and dielectric substrate:A contrastive study

Hybrid plasmon waveguides, respectively, with metamaterial substrate and dielectric substrate are investigated and analyzed contrastively with a numerical finite element method. Basic properties, including propagation length Lp, effective mode area Aeff, and energy distribution, are obtained and compared with waveguide geometric parameters at 1.55 gin. For the waveguide with metamaterial substrate, propagation length Lp increases to several tens of microns and effective mode area Aeff is reduced by more than 3 times. Moreover, the near field region is expanded, leading to potential applications in nanophotonics. Therefore, it could be very helpful for improving the integration density in optical chips and developing functional components on a nanometer scale for all optical integrated circuits.

Tunable coupling of a hybrid plasmonic waveguide consisting of two identical dielectric cylinders and a silver film

The propagation length of surface plasmon polaritons（SPPs） is intrinsically limited by the metallic ohmic loss that is enhanced by the strongly confined electromagnetic field. In this paper, we propose a new class of hybrid plasmonic waveguides（HPWs） that can support long-range SPP propagation while keeping subwavelength optical field confinement. It is shown that the coupling between the waveguides can be well tuned by simply varying the structural parameters. Compared with conventional HPWs, a larger propagation length as well as a better optical field confinement can be simultaneously realized. The proposed structure with better optical performance can be useful for future photonic device design and optical integration research.

Terahertz multi-metal-wire hybrid-cladding hollow waveguide for refractive index sensing

We propose a design of terahertz refractive index sensing based on the multi-metal-wire（MMW） hybrid-cladding hollow waveguide. The proposed terahertz hybrid-cladding hollow waveguide comprises one air core in the center surrounding MMW surrounded dielectric. The central air core is used for filling lossless measurands and transmitting terahertz light. In particular, the refractive index sensing is realized by measuring the mode field area（MFA） variation of radially polarized mode. The modal effective refractive index, mode field intensity distribution, and mode field area properties responding to the measurand refractive indexes for different operating frequencies and structure dimensions are investigated, respectively.Simulations show that the proposed terahertz refractive index sensor can realize easily the measurement of the measurand refractive index. Meanwhile, the effects of operating frequency and structure parameters on sensitivity and measurement accuracy are also studied. In view of the trade-off between sensitivity and measurement accuracy, the reasonable choice of the operating frequency and structure parameters can optimize appropriately the sensitivity and measurement accuracy, and the sensitivity can reach approximately 0.585 mm^2/RIU（RIU is short for refraction index units） with the proper frequency and structure parameter.

石墨烯混合等离子体波导光子轨道角动量产生及转换器设计

为满足现代社会对通信容量日益增长的需求,设计了一种基于石墨烯混合等离子体波导的可重构光子轨道角动量产生及转换器,利用时域有限差分法对器件的性能进行了仿真分析.仿真结果表明:石墨烯费米能级为0 eV时,该装置实现了拓扑荷由+1向−1或者−1向+1的光子轨道角动量的转换,转换效率达到93.6%;石墨烯费米能级为0.9 eV时,该装置可以将线偏振光转换为携带轨道角动量的涡旋光,此时该器件还可以用于识别拓扑荷为±1的涡旋光.

基于横向耦合和正交耦合的基片集成波导超宽阻带滤波功分器

基片集成波导滤波功分器在通信系统中的应用逐渐广泛。与传统波导谐振器相同,基片集成波导谐振器含有多个传输模式,导致基片集成波导滤波器的宽阻带特性很难实现。本文设计了一种由电激励实现的超宽阻带基片集成波导滤波功分器。具体地,提出了一种基于电磁交替耦合拓扑的四阶基片集成波导滤波功分器,具有电输入和电输出端口。横向耦合通过谐振腔侧边开窗实现磁耦合,纵向耦合通过在相邻两腔之间的耦合窗口中蚀刻S槽线实现电耦合。通过正交传输路径可以抑制多个高阶模式,仿真和测量结果表明,阻带带宽分别大于9f 0和3.1f 0范围,该中心频率为35.5 GHz的滤波功分器的带外抑制效果优于-20 dB。上述方法经实物验证,试验结果与仿真结果吻合。

基于电磁混合耦合的SIW宽阻带带通滤波器设计

为实现阻带一段范围内依然具有良好的抑制能力,提出了电磁混合耦合的基片集成波导(Substrate Integrated Waveguide,SIW)宽阻带带通滤波器(Bandpass Filter,BPF)。根据模式的本征抑制和电磁混合耦合理论,合理地设置外部馈电端口、内部耦合窗口及内部耦合圆孔阵列,抑制了频率低于TE_(105)和TE_(501)之前的所有高次模,并且使得工作模式TE101电耦合很好地传输。仿真与实测结果均显示,该滤波器的中心频率f_(0)=5.94 GHz,插入损耗为−3.46 dB,相对带宽为2.44%,当阻带宽度延伸至3.85 f0时,抑制深度优于20 dB。与经典的四阶SIW宽阻带带通滤波器相比,拥有相同的带宽时,该双层层叠的方式更加紧凑,有利于集成到微波电路系统中。

Numerical Investigation of Phase and Group Propagation of Time-Domain Signals in a Novel Band-Reject Metamaterial Ring Hybrid

Phase and group propagation in metamaterial-based microwave components has always been intellectually challenging for students and engineers new to the area of periodic structures and metamaterials. This paper aims in tackling this important topic by studying the wave propagation in a metamaterial-based microwave device. Hence, the contribution of this paper is twofold. First, design of a novel metamaterial ring hybrid (or rate-race) is presented which has a large rejection band so that the second and third harmonics are effectively suppressed. Second, the electromagnetic phase and the group propagation in the ring hybrid are investigated by numerically exciting the input ports with band-limited Gaussian pulses and then finding their responses at various locations in the device.

基于多层结构的宽阻带SIW带通滤波器

近年来,多层结构的基片集成波导(SIW)带通滤波器因其结构紧凑的优点得到研究者们的青睐,与此同时,阻带带宽窄的缺点又阻碍了滤波器的发展。为了提升滤波器的阻带性能,提出一种基于多层结构的宽阻带SIW带通滤波器。将滤波器的内外耦合窗口设置在模式的最弱电场处,从本质上抑制该模式。同时引入电磁混合耦合理论,分析特定模式的电磁分布情况,并根据HFSS软件提取的耦合系数设计耦合孔径的大小和位置,实现对特定模式的抑制。仿真结果显示可以完全抑制谐振频率低于TE_(303)模以内的所有高次模。实际加工并测量了该滤波器,中心频率为5.9 GHz,相对带宽为2.54%,阻带可以延伸至17.42 GHz (2.95f_(0),f_(0)为滤波器中心频率),且带外抑制优于28 dB,仿真和测量结果显示两者吻合度较好。与其他SIW滤波器相比,该方法设计简单、带宽可调、阻带更宽,易于应用到实际的微波通信系统中,具有潜在的应用价值。

Fast response 2×2 thermo-optic switch with polymer/silica hybrid waveguide

A polymer/silica hybrid 2×2 multimode-interference switch is designed and fabricated. Instead of polymer Mach-Zehnder interferometer thermo-optic （TO） silica is used as under-cladding to accelerate heat release because of its large thermal conductivity. The developed switch exhibits low power consumption of 6.2 mW, low crosstalk of about 28 dB, and short response time. The rise and fall times of 103 and 91 its for this hybrid switch are shortened by 40.8% and 52.4%, respectively, compared with those of the fabricated TO switch （174 and 191 μs） using polymer as both upper- and under-claddings.

Hybrid silicon slotted photonic crystal waveguides:how does third order nonlinear performance scale with slow light?

We investigate in this paper the influence of slow light on the balance between the Kerr and two-photon absorption(TPA) processes in silicon slotted hybrid nonlinear waveguides. Three typical silicon photonic waveguide geometries are studied to estimate the influence of the light slow-down factor on the mode field overlap with the silicon region, as well as on the complex effective nonlinear susceptibility. It is found that slotted photonic crystal modes tend to focalize in their hollow core with increasing group index(n_G) values. Considering a hybrid integration of nonlinear polymers in such slotted waveguides, a relative decrease of the TPA process by more factor of 2 is predicted from n_G=10 to n_G=50. As a whole, this work shows that the relative influence of TPA decreases for slotted waveguides operating in the slow light regime, making them a suitable platform for third-order nonlinear optics.

紧凑型纳米薄膜铌酸锂复合波导光电子可逆逻辑门

基于纳米薄膜铌酸锂与氮化硅复合波导结构,构建了光电子可逆逻辑门,应用于神经形态光子学和量子计算。该光电子可逆逻辑门的主体由两个马赫-曾德尔调制器级联而成,结构紧凑,全长仅为4.4 mm,是普通质子交换铌酸锂调制器长度的百分之一。工作在1.55μm波长时,该马赫-曾德尔调制器仅需4.9 V电压就可以实现一次完整的功率交换,很好地与CMOS工艺相兼容。器件特性研究表明,该光电子可逆逻辑门能够实现可逆逻辑运算功能。此外,该器件在1.4~1.6μm波长范围内,插入损耗均值为0.6 dB,输出端口的最小串扰为-47 dB,消光比的最大值为41 dB;在4~6 V电压范围内,插入损耗均值为0.63 dB,输出端口的最小串扰为-26 dB,消光比的最大值为22 dB,显示出了良好的响应特性。

Optical Waveguides from Organic/Inorganic Hybrid Materials

Organic/inorganic material has attracted great attentions because its importance as photonic materials. We report on our recent results on organic/inorganic hybrid sol-gel materials and optical waveguides like splitter, thermo-optic switch and micro-cavity laser.

Energy intensity analysis of modes in hybrid plasmonic waveguide

A hybrid plasmonic waveguide containing silicon core, silver cap and ultra-thin sandwiched SiO2 layer is studied. By analyzing the mode distribution patterns and the curves of mode effective index, we show how the plasmonic mode around the metal surface is coupled with the fundamental mode in the silicon core to form a squeezed hybrid mode. The ability of the hybrid plasmonic waveguide in energy confinement is also discussed quantitatively.

基于厚薄膜混合封装基板的射频系统级封装设计

采用芯片倒装的形式可以有效解决高功率微波芯片系统级封装(SIP)的散热问题,但基于厚膜工艺的LTCC/HTCC封装基板与倒装芯片存在尺寸失配、无法直接互联的问题.为此设计了一种基于厚薄膜混合技术的封装基板.首先通过内部采用传统厚膜工艺、表面采用薄膜布线工艺的厚薄膜混合技术解决了芯片与封装基板尺寸失配的问题;然后对与芯片匹配的带地共面波导(CPWG)尺寸进行设计,采用梯形过渡结构使之与封装基板垂直过孔尺寸匹配;最后通过热仿真验证了该结构的系统散热性能.仿真结果表明,在射频性能良好情况下,本文封装结构散热性能优于传统形式封装.

Nonlinear hybrid plasmonic slot waveguide for second-harmonic generation

A nonlinear hybrid plasmonic slot waveguide composed of periodically poled lithium niobate(PPLN) and two separated silver films is investigated. The e?ective refractive index, propagation length, and energy confinement of the hybrid anti-symmetric mode in this waveguide are calculated using the structure parameters at the fundamental wavelength of λ = 1550 nm and its second harmonic(SH) λ = 775 nm. Through the above indices, coupling e?ciency(maximum SH conversion e?ciency during propagation) and peak position(propagation location of the conversion e?ciency) of SH generation are analyzed. Finally, higher conversion e?ciency can be achieved at a shorter propagation distance by changing the waveguide into a tapered structure.

A mechanical reliability study of 3-dB waveguide hybrid couplers in submillimeter and terahertz bands

This paper presents a mechanical reliability study of 3-dB waveguide hybrid couplers in submillimeter and terahertz bands.To show the necessity of improving the mechanical properties of the coupler’s branch in submillimeter and terahertz bands,a comprehensive study regarding the displacement of hybrid branch variation with varying width-length ratio and height-length ratio has been completed.In addition,a modified 3-dB waveguide hybrid coupler is designed and presented.Compared with the traditional branch structure,the proposed hybrid consists of a modified middle branch with circular cutouts at the top and bottom on both sides instead of the traditional rectangle branch,which increases the branch size and improves its mechanical reliability while achieving the same performance.Simulation results show that the deformation of the modified hybrid branch is 22%less than those of other traditional structure designs under the same stress.In practice,a vibration experiment is set up to verify the mechanical reliability of hybrid couplers.Measurement results show that the experiment deteriorates the coupling performance.Experimental results verify that the performance of the novel structure coupler is better than that of a traditional structure branch hybrid coupler under the same electrical properties.

Polarization-Insensitive Hybrid Plasmonic Waveguide Design for Evanescent Field Absorption Gas Sensor

We propose a polarization-insensitive design of a hybrid plasmonic waveguide(HPWG)optimized at the 3.392µm wavelength which corresponds to the absorption line of methane gas.The waveguide design is capable of providing high mode sensitivity(Smode)and evanescent field ratio(EFR)for both transverse electric(TE)and transverse magnetic(TM)hybrid modes.The modal analysis of the waveguide is performed via 2-dimension(2D)and 3-dimension(3D)finite element methods(FEMs).At optimized waveguide parameters,Smode and EFR of 0.94 and 0.704,can be obtained for the TE hybrid mode,respectively,whereas the TM hybrid mode can offer Smode and EFR of 0.86 and 0.67,respectively.The TE and TM hybrid modes power dissipation of~3 dB can be obtained for a 20-µm-long hybrid plasmonic waveguide at the 60%gas concentration.We believe that the highly sensitive waveguide scheme proposed in this work overcomes the limitation of the polarization controlled light and can be utilized in gas sensing applications.