Nanoscale light confinement and transport in symmetric hybrid plasmonic waveguides based on silicon nanoslots

正Light confinement at the nanoscale beyond the fundamental diffraction limit is of critical importance to the advancement of next-generation photonic technology,since it offers unprecedented opportunities with dramatically enhanced light-matter interactions.A silicon-nanoslot based symmetric hybrid structure was reported,capable of providing low propagation loss,subwavelength mode size and tight field confinement inside the low-index gap region.The nice optical performance in conjunction with several unique features could enable a number of further applications.In addition to the waveguide proposed here,a number of alternative guiding schemes could also be employed to achieve the goal of propagation loss reduction with subwavelength mode confinement,including structures based on horizontal slot waveguides,and many other configurations capable of forming symmetric or near-symmetric environment along with high-index contrast near the metallic waveguides,such as metal nanostructures covered by low-high-index dielectrics supported by low-index substrates,and coaxial type-structures consisting of metallic nanowires surrounded by dielectrics.     

环氧树脂多模光波导的研制

以环氧树脂为材料,用简单、低成本的非接触式光 刻法制作多模光波导。通过实验,找出一种可靠有效的有机溶剂作为 显影剂及其相应的显影时间; 并研究了温湿度和旋涂工艺对光波导厚度的影响;以及光刻掩模版透光部分宽度、光刻 掩模版与下包 层之间的间距、曝光光强和曝光时间对光波导宽度的影响。扫描电子显微镜(SEM)对 样品形貌分析表明,脊形光波导表面光滑且侧壁笔直,光波导芯横截面约为 50μm×50μm。采用cut-back法,测出环氧树脂多模光波导的传输损耗为0.1dB/cm@850nm。考虑到 光电集成过程中对光波导的高温冲击,对样品进行了热稳定性试验,获得的最高稳定温 度为210℃。     

玻璃基片上双层多模光波导的制备

在光学玻璃基片上制作了双层掩埋式多模光波导芯片,这种芯片中的上、下两层光波导均通过熔盐离子交换和电场辅助离子迁移形成。对光波导的横截面以及输出光斑进行了观察,并进行了损耗和串扰测试。研究结果表明:双层多模光波导芯片中上、下两层光波导芯部横截面尺寸分别为29 m19 m和31 m20 m;两层波导的输出光斑尺寸相互匹配;两层波导传输损耗分别为1.000.32 dB/cm和0.780.35 dB/cm;两层光波导之间的串扰在17.7dB左右。这种玻璃基片上的双层多模光波导可以使板级光互连的互连密度增大一倍,提高EOCB的性能。     

Low-cost and low-loss multimode waveguides of photodefinable epoxy

To satisfy the urgent need for low-cost multimode planar waveguides, we developed photodefined, multimode-fiber compatible waveguides with low-cost commercially available epoxies showing low losses from 550 to 1100 nm and around 1300nm.     

Field-induced index profiles of multimode ion-exchanged strip waveguides

The index profiles of multimode strip waveguides, which are fabricated and buried by field-assisted ion exchange processes in glasses, follow from the distribution of the applied drift field. A comparison between theoretical solutions and accurate measurements of the two-dimensional index profiles confirms that a precise calculation in terms of the technological parameters is possible.     

Asymmetric dark modes in symmetric nonlinear waveguides

We show that symmetric nonlinear waveguides can support the asymmetric dark modes. The existence of a novel class of bright nonlinear guided wave with nonzero-intensity background is also demonstrated     

Power attenuation in bent multimode step-index slab and fibre waveguides

The power attenuation induced by a circular bend in the waveguide axis is calculated using ray tracing and a generailsed power-transmission coefficient for the case of diffuse illumination.     

多模厚深波导的快速制作与测试

在玻璃基板上用Li~+-Na+离子交换技术快速制作与多模光纤有较高耦合效率的多模厚深波导,并分析了测试结果。     

Multichannel optical splitters based on planar multimode silica-glass waveguides

The calculated optical characteristics and the technology for the structure formation of multichannel optical splitters are presented. The splitters are based on planar optical waveguides made of silica glass obtained via microwave plasma chemical deposition. Multimode splitters of the 16 × 16 type for the fiber optic data-transmission systems are produced with the use of the planar waveguides.     

Low-loss singlemode amorphous silicon waveguides

Amorphous silicon waveguides were obtained by plasma-enhanced chemical vapour deposition and anisotropic plasma etching. Rectangular multimode waveguides as well as singlemode ridge waveguides were fabricated. Scattered light measurements at 1550 nm (1300 nm) wavelength showed a low propagation loss of /spl les/0.5 dB/cm (1.6 dB/cm) for multimode waveguides and 2.0 dB/cm (5.0 dB/cm) for highly-confined singlemode waveguides.     

System experiments with multimode waveguides and fibers forapplications in computer interconnects

The effect on the modal noise induced bit-error-rate floor when passing light through short lengths (0.5→70 mm) of large core epoxy ridge waveguides and multimode fibers was investigated. It was demonstrated that the bit-error-rate floor declines rapidly with the waveguide transmission distance, whereas for the multimode fiber the floor is independent of the length. The issue of estimating modal noise bit-error-rate floors at realistic levels of the mode selective loss is addressed. The experimental set-up is discussed, and the results of modal noise system experiments performed at 1 Gb/s non-return-to-zero (NRZ) are presented. Worst-case requirements to the waveguide design are discussed     

A novel mode content analysis technique for antennas in multimode waveguides

This paper presents a novel technique for analyzing the mode content excited by antennas placed in multimode waveguides. The technique is based on measuring the frequency response between the two antennas coupled into a waveguide and using that information to extract the mode content generated by the transmitting antenna. The technique is applicable to cases in which the mode amplitudes are approximately constant over the frequency range of interest. This method is valuable for determining the mode mix generated by arbitrary transmitting antennas in a multimode waveguide propagation environment. An example of such an environment is heating, ventilation, and air-conditioning (HVAC) ducts used for indoor communications, where an important antenna characteristic is the mode sensitivity (analogous to the antenna directive gain in free space). We validate our technique with the example of a monopole probe antenna coupled into a multimode cylindrical HVAC duct.     

Novel mode scrambler for reducing mode dependence in multimode optical waveguides

A novel mode scrambler for multimode optical waveguides is proposed to stabilise branching characteristics against the mode excitation conditio. A 2 × 2 optical star coupler is fabricated using this mode scrambler, and a stable branching ratio is realised with an excess insertion loss of 2.7 dB.     

Bending properties in oxidized porous silicon waveguides

The greatest limit in high-speed communications between different circuit blocks is due to the delays introduced by metal interconnections. Knock-down wire communication bottleneck is, therefore, one of the best goals that current research could reach in the field of fast electronics. A possible solution is to build fast optical links and even better if the technology is based on silicon. To attain these ends, we have made studies into possibility to fabricate optical waveguide based on oxidized porous silicon. In the last few years, such a device was realized and characterized. Waveguiding in the visible and in the near infrared was demonstrated, with propagation losses of about 3–5 dB/cm for a light with a wavelength of 632.8 nm. Moreover, a design feature of an integrated waveguide based on oxidized porous silicon is that it offers a spontaneous bending of the waveguiding layer at its ends. The edge bending is provided by a convex camber of a leading edge of forming porous silicon. This bending can be exploited to promote a vertical light output with no use of any additional devices. The paper discusses the properties of edge bending, evaluation of the light losses depending on the radius of curvature, and analysis of possibilities to reduce these losses.     

Fast fabrication method for thick and highly multimode optical waveguides

A eutectic melt of lithium and potassium sulphates was used to fabricate thick, low-loss and highly multimode waveguides by ion exchange in glass.     

用于光互连的聚硅氧烷脊型光波导研究

采用软成型和图案转移技术,制备了可用于高速芯片间光互连的大尺寸聚硅氧烷脊型光波导,光波导长度达23cm.利用有效折射率法,对芯层残留层和传输模场的关系进行了分析.采用截断和数字化散射两种方法,测得输入光波长为633nm时的平均传输损耗小于0.14dB/cm.研究结果表明,波导的长度和损耗指标满足高速芯片间光互连的要求.     

Single-mode condition for silicon rib waveguides

The geometrical conditions required for single-mode propagation in large cross-section silicon-on-insulator (SOI) waveguides were investigated using the beam propagation method (BPM). The cases of both vertical-walled and sloping-walled (trapezoidal) rib structures were considered. In the trapezoidal case some approximate methods were compared with the simulated results. Expressions for the single-mode condition for both types of waveguide were defined.     

Surface emitting characteristics of silicon waveguides

This paper concerns the surface emitting characteristics of silicon waveguides in the millimeter-wave frequency band. The waveguides used in the experiment are rectangular slabs of high resistivity silicon (30,000 ohm-cm). A series of periodic perturbations on the waveguide surface provide a radiating antenna. A rectangular grating with a period of Λ=1.8 mm, a height of 0.35 mm, and a duty cycle of 0.46 was sawn into the top surface of a silicon waveguide with a width of 3 mm and a height of 1.41 mm. Experiments were performed to measure the attenuation, dispersion and the radiation characteristics of the waveguides. The test setup was used to monitor the frequency, radiation angle, and the radiated power. Measurements are made over a band of frequencies around the second Bragg frequency. The detector was scanned from 88–95 GHz and changes were observed in the attenuation constant, dispersion relation and the far field radiation pattern. From these results we were able to verify the grating theory.     

Two-dimensional silicon nanomaterials for optoelectronics

Silicon nanomaterials have been of immense interest in the last few decades due to their remarkable optoelectronic responses, elemental abundance, and higher biocompatibility. Two-dimensional silicon is one of the new allotropes of silicon and has many compelling properties such as quantum-confined photoluminescence, high charge carrier mobilities, anisotropic electronic and magnetic response, and non-linear optical properties. This review summarizes the recent advances in the synthesis of two-d...