47. Yusheng Bian, e al., "Hybrid vanadate waveguiding configurations for extreme optical confinement and efficient polarization management in the near-infrared," Nanoscale 10, 16667 - 16674 (2018). (Impact Factor: 7.394)
Vanadate materials such as CaVO3 and SrVO3 were recently proposed as promising alternatives to their conventional transparent conducting oxide counterparts owing to the superior capability for simultaneous realization of high optical transparency and high electrical conductivity originating from strong electron–electron interactions. Here we show that, in addition to their remarkable optoelectronic properties as conducting materials, their incorporation into planar waveguiding configurations could enable outstanding optical performance that is otherwise difficult to achieve with conventional material building blocks, especially metals. Starting from the guided wave at a single CaVO3/dielectric interface, the unique dispersion relationship and propagation property of the fundamental mode are revealed and compared to the conventional surface plasmon polariton associated with a silver/dielectric planar configuration. The superior confinement capability and the unique modal attenuation of the CaVO3-based waveguiding platform are further demonstrated viainvestigating silicon-based hybrid guiding schemes integrated with a CaVO3 nanostructure. By leveraging the pronounced polarization dependent loss in the hybrid configuration, an ultra-compact TE-pass polarizer is numerically demonstrated at telecommunication wavelengths. This transformative design features a reduced footprint and enhanced optical performance when benchmarked against the current state-of-the-art in hybrid silicon polarizers. The combination of these vanadate materials with traditional waveguiding platforms thereby opens new avenues towards miniaturized functional integrated photonic devices, and potentially enables a variety of intriguing applications at the sub-diffraction-limited scale.
45. Yusheng Bian et al., "Efficient Cross-talk Reduction of Nanophotonic Circuits Enabled by Fabrication Friendly Periodic Silicon Strip Arrays," Scientific reports 7 (1), 15827 (2017). (Impact Factor: 4.122)
Reduction of the crosstalk between adjacent photonic components has been regarded as one of the most effective, yet most challenging approaches for increasing the packing density of photonic integrated circuits. Recently, extensive efforts have been devoted to this field, leading to a number of elaborate designs, such as waveguide supperlattice and nanophotonic cloaking, among others. Here we develop a simple and efficient crosstalk reduction approach for silicon-based nanophotonic circuits by introducing a periodic array of silicon strips between adjacent waveguides. Studies indicate that the coupling lengths can be extended by more than two orders of magnitude for a waveguide pair with an edge-to-edge distance of ~λ/3 at the telecommunication wavelength. Further investigations reveal that our method is effective for both strongly and weakly confined silicon photonic modes, and works well over a broad band of operational wavelengths. In addition, the crosstalk reduction technique is shown to be capable of improving the coupling lengths of other elements as well, such as vertical silicon slot waveguides. Our approach offers a promising platform for creating ultra-compact functional components that is fabrication friendly, thereby providing a feasible route toward the realization of photonic integrated circuits with ultra-high packing densities
46. Yusheng Bian et al., "Deep-subwavelength light transmission in hybrid nanowire-loaded silicon nano-rib waveguides," Photonics Research 6 (1), 37-45 (2017). (Impact Factor: 5.242)
Hybrid plasmonic waveguides leveraging the coupling between dielectric modes and plasmon polaritons have emerged as a major focus of research attention during the past decade. A feasible way for constructing practical hybrid plasmonic structures is to integrate metallic configurations with silicon-on-insulator waveguiding platforms. Here we report a transformative high-performance silicon-based hybrid plasmonic waveguide that consists of a silicon nano-rib loaded with a metallic nanowire. A deep-subwavelength mode area (𝜆2/4.5×105−𝜆2/7×103λ2/4.5×105−λ2/7×103), in conjunction with a reasonable propagation distance (2.2–60.2 μm), is achievable at a telecommunication wavelength of 1.55 μm. Such a nano-rib-based waveguide outperforms its conventional hybrid and plasmonic waveguiding counterparts, demonstrating tighter optical confinement for similar propagation distances and a significantly enhanced figure of merit. The guiding properties of the fundamental mode are also quite robust against possible fabrication imperfections. Due to the strong confinement capability, our proposed hybrid configuration features ultralow waveguide cross talk and enables submicron bends with moderate attenuation as well. The outstanding optical performance renders such waveguides as promising building blocks for ultracompact passive and active silicon-based integrated photonic components.
44. Qiang Ren, Yusheng Bian, et al., "Leap-Frog Continuous–Discontinuous Galerkin Time Domain Method for Nanoarchitectures With the Drude Model," Journal of Lightwave Technology 35 (22), 4888-4896(2017) (Impact Factor: 3.652)
A continuous–discontinuous Gakerkin time domain method (CDGTD) with vector basis functions is proposed to analyze the wideband response of plasmonic structures with the Drude dispersive model. Compared to the conventional time domain approaches, such as FDTD and PSTD, the unstructured mesh can provide a better geometrical approximation of curved surfaces and fine features. An EB scheme Riemann solver is employed to calculate the flux between adjacent subdomains. The relationship between the electric field and the polarization currents is modeled by a first order auxiliary differential equation (ADE). A leap-frog scheme is proposed to update Maxwell's equations, the ADEs of the Drude medium and the perfectly matched layer (PML) in an efficient manner. This new approach is validated by virtue of simulating the ultra-wideband behavior of a gold nanoloop antenna with and without a substrate as well as the reflectivity of a dual-band infrared absorber. Its advantage in computational cost is demonstrated via comparison to a commercial software package. In this light, the CDGTD method represents a more efficient forward modeling tool, which has been successfully employed here to perform a parametric study of a dual-band infrared absorber.
43. Yusheng Bian, and Qihuang Gong, "Metallic-nanowire-loaded silicon-on-insulator structures: a route to low-loss plasmon waveguiding on the nanoscale," Nanoscale 7(10), 4415 - 4422 (2015). (Impact Factor: 7.394) “Inside back cover of the issue” [Link] [PDF]
The simultaneous realization of nanoscale field localization and low transmission loss remains one of the major challenges in nanophotonics. Metal nanowire waveguides can fulfill this goal to a certain extent by confining light within subwavelength space, yet their optical performances are still restricted by the tradeoff between confinement and loss, which results in quite limited propagation distances when their mode sizes are reduced down to the nanometer scale. Here we introduce a class of low-loss guiding schemes by integrating silicon-on-insulator (SOI) waveguides with plasmon nanowire structures. The closely spaced silicon and metal configurations allow efficient light squeezing within the nanometer, low-index silica gaps between them, enabling deep-subwavelength light transmission with low modal attenuation. Optimizations of key structural parameters unravel the wide-range existence of the high-performance hybrid nanowire plasmon mode, which demonstrates improved guiding properties compared to the conventional hybrid and nanowire plasmon polaritons. The excitation strategy of the guided mode and the feasibility of the waveguide for compact photonic integration as well as active components are also discussed to lay the foundation for its practical implementation. The remarkable properties of these metallic-nanowire-loaded SOI waveguides potentially lend themselves to the implementation of high performance nanophotonic components, and open up promising opportunities for a variety of intriguing applications on the nanoscale.
42. Yusheng Bian, and Qihuang Gong, "Bow-tie hybrid plasmonic waveguides," Journal of Lightwave Technology 32(23), 3902-3907 (2014). (Impact Factor: 2.965) [Link] [PDF]
We propose a hybrid plasmonic waveguide that incorporates a semiconductor—insulator–metal bow-tie configuration within a low-index gap guarded by semiconductor and metallic nanostructures. Ultratight field confinement (Aeff∼λ2/3100 −λ2/120) in conjunction with reasonable propagation distance (L∼56-138μm) can be achieved simultaneously at a telecommunication wavelength. Compared to a conventional hybrid waveguide, the effective mode area and propagation loss of a typical bow-tie hybrid configuration are reduced by 2–89% and 34–62%, respectively, whereas the figure of merit is enhanced by 53–700%, along with increased power ratio inside the gap region for small gap cases. Studies on fabrication tolerance, waveguide crosstalk, and loss compensation reveal its robust property for practical implementations and remarkable feasibility to realize ultracompact passive and active components. Moreover, we also reveal the broadband feature of the waveguide and show that its concept can be applicable to various other metallic configurations as well, whichmay open up possibilities for the inventions of numerous high-performance plasmon waveguides and components.
41. Yusheng Bian, and Qihuang Gong, "Tuning the hybridization of plasmonic and coup led dielectric nanowire modes for high-performance optical waveguiding at sub-diffraction-limited scale," Scientific Reports 4, 6617 (2014). (Impact Factor: 5.578) [Link]
We report the realization of low-loss optical waveguiding at telecommunication wavelength by exploiting the hybridization of photonic modes guided by coupled all-dielectric nanowires and plasmon waves at planar metal-dielectric interfaces. The characteristics of the hybrid plasmon polaritons, which are yielded by the coupling between two types of guided modes, can be readily tuned through engineering key structural parameters of the coupled nanowires and their distances to the metallic surfaces. In addition to exhibiting significantly lower attenuations for similar degrees of confinement as compared to the conventional hybrid waves in single-dielectric-nanowire-based waveguides, these hybridized plasmonic modes are also capable of enabling reduced waveguide crosstalk for comparable propagation distances. Being compatible with semiconductor fabrication techniques, the proposed guiding schemes could be promising candidates for various integrated photonic devices and may lead to potential applications in a wide variety of related areas.
40. Yusheng Bian, and Qihuang Gong, "Highly confined guiding of low-loss plasmon waves in hybrid metal-dielectric slot waveguides," Nanotechnology 25(34), 345201 (2014). (Impact Factor: 3.821) [Link] [PDF]
We report the observation of strongly confined plasmon modes in hybridized metal-dielectric slot waveguides, which consist of semiconductor–insulator–semiconductor nanostructures embedded inside the low-index gaps of conventional hybrid plasmonic configurations. Owing to the combined effects induced by the high-refractive-index-contrast dielectric slot and semiconductor–insulator–metal configurations, tight field localization (Aeff∼λ2/1250 λ2/55) in conjunction with large propagation distances (L∼70–180 μm) can be realized simultaneously at telecommunication wavelength. Through comprehensive numerical simulations, the characteristics of the fundamental hybrid modes are revealed in detail by optimizing key structural parameters of the waveguides. The advantages over their traditional hybrid waveguiding counterparts are unraveled. In addition, the possibilities of extending our current design into other metal/dielectric composites are also discussed. Our studies regarding hybrid metal-dielectric slot structures and their alternatives in this paper are expected to provide effective approaches for the enhancement of traditional hybrid modes’ properties and open up new opportunities for the constructions of high-performance plasmon waveguides and devices.
39. Yusheng Bian, and Qihuang Gong, "Long-range hybrid ridge and trench plasmonic waveguides," Applied Physics Letters 104(25), 251115 (2014). (Impact Factor: 3.302) [Link] [PDF]
We report a class of long-range hybrid plasmon polariton waveguides capable of simultaneously achieving low propagation loss and tight field localization at telecommunication wavelength. The symmetric (quasi-symmetric) hybrid configurations featuring high-refractive-index-contrast near the non-uniform metallic nanostructures enable significantly improved optical performance over conventional hybrid waveguides, exhibiting considerably longer propagation distances and dramatically enhanced figure of merits for similar degrees of confinement. Compared to their traditional long-range plasmonic counterparts, the proposed hybrid waveguides put much less stringent requirements on index-matching conditions, demonstrating nice performance under a wide range of physical dimensions and robust characteristics against certain fabrication imperfections. Studies concerning crosstalk between adjacent identical waveguides further reveal their potential for photonic integrations. In addition, alternative configurations with comparable guiding properties to the structures in our case studies are also proposed, which can potentially serve as attractive prototypes for numerous high-performance nanophotonic components.
38. Yusheng Bian, and Qihuang Gong, "Nanotube based hybrid plasmon polariton waveguide for propagation loss reduction and enhanced field confinement inside the gap region at the subwavelength scale," Photonics and Nanostructures - Fundamentals and Applications 12(3), 259-267 (2014). (Impact Factor: 1.474) “Most Downloaded Photonics and Nanostructures Articles“ [Link] [PDF]
We present a comprehensive numerical investigation on the guiding properties of a nanotube based hybrid plasmonic waveguide, which comprises a high-index dielectric nanotube placed above a metallic substrate. It is shown that the incorporation of the nanotube offers additional freedom for tuning the optical performance of the hybrid plasmonic structure when compared to the traditional nanowire based hybrid counterparts, which enables further reduction of the propagation loss and enhanced field confinement inside the gap region, while simultaneously maintaining a subwavelength mode size at appropriate geometries. Systematic geometric parameters mapping considering the size of the nanotube and the dimension of the gap reveals that the tradeoff between the confinement and loss could be further balanced through optimizing key physical parameters. These investigations potentially lay the groundwork for the further applications of nanotube based hybrid structures.
37. Yusheng Bian, and Qihuang Gong, "Compact all-optical interferometric logic gates based on one-dimensional metal–insulator–metal structures," Optics Communications 313, 27-35 (2014). (Impact Factor: 1.449) [Link] [PDF]
The whole set of fundamental all-optical logic gates is realized theoretically using a multi-channel configuration based on one-dimensional (1D) metal-insulator-metal (MIM) structures by leveraging the linear interference between surface plasmon polariton modes. The working principle and conditions for different logic functions are analyzed and demonstrated numerically by means of the finite element method. In contrast to most of the previous studies that require more than one type of configuration to achieve different logic functions, a single geometry with fixed physical dimensions can realize all fundamental functions in our case studies. It is shown that by switching the optical signals to different input channels, the presented device can realize simple logic functions such as OR, AND and XOR. By adding signal in the control channel, more functions including NOT, XNOR, NAND and NOR can be implemented. For these considered logic functions, high intensity contrast ratios between Boolean logic states "1" and "0" can be achieved at the telecom wavelength. The presented all-optical logic device is simple, compact and efficient. Moreover, the proposed scheme can be applied to many other nano-photonic logic devices as well, thereby potentially offering useful guidelines for their designs and further applications in on-chip optical computing and optical interconnection networks.
36. Yusheng Bian, and Qihuang Gong, "Deep-subwavelength light confinement and transport in hybrid dielectric-loaded metal wedges," Laser & Photonics Reviews 8(4), 549-561 (2014). (Impact Factor: 8.008) “Back cover of the issue” [Link] [PDF]
The goal of confining light at the deep-subwavelength scale while retaining moderate attenuation has been pursued for years in the field of plasmonics. However, few feasible configurations at present are excellent at balancing the tradeoff between confinement and loss. This work proposes to overcome the above limitation by using hybrid wedge structures, which consist of triangular metal wedges loaded with nanometric low/high-index dielectric claddings. Owing to the superior guiding properties of wedge plasmons in conjunction with high refractive index contrast near wedge tips, the modal sizes can be squeezed into significantly smaller spaces than those of their conventional wedge and planar hybrid counterparts, while simultaneously featuring propagation distances over tens of micrometers at telecommunication wavelengths. Studies on the evolution from a single metallic wedge to semiconductor–insulator–metal wedge(s) reveal strategies for continuous improvement of the optical performance. Discussions concerning practical issues including crosstalk and mode excitation have further elucidated their potential in building high-performance nanophotonic components.
35. Yusheng Bian, and Qihuang Gong, "Multilayer metal-dielectric planar waveguides for subwavelength guiding of long-range hybrid plasmon polaritons at 1550 nm," Journal of Optics 16(1), 015001 (2014). (SCI:000328623600001, Impact Factor: 2.059) "Selected in 'Highlights of 2014' collection of Journal of Optics" [Link] [PDF]
The characteristics of long-range hybrid plasmonic modes guided by multilayer metal–dielectric planar waveguides are investigated at the telecom wavelength. These multilayer structures are formed by sandwiching thin metallic stripes into horizontal silicon slot-like waveguides. Comprehensive numerical studies regarding the geometric parameters’ effects on the modal properties reveal that, by properly choosing the dimensions of the metal stripe and the low-index gaps between the stripe and the silicon layers, the symmetric hybrid modes supported by the structures could feature simultaneously ultra-long propagation distance (several centimeters) and subwavelength mode size. Consideration of possible fabrication imperfections shows that the optical performances of the waveguides are quite robust and highly tolerant to these errors. The presented multilayer plasmonic structures greatly extend the capabilities of conventional long-range surface plasmon polariton waveguides by successfully confining light into a subwavelength scale while maintaining the key advantage of enabling ultra-low-loss propagation, which could facilitate potential applications in ultra-long-range plasmon waveguiding and realizations of compact, high-performance photonic components, as well as building optically integrated circuits with complex functionalities.
34. Yusheng Bian, and Qihuang Gong, "Deep-subwavelength light routing in nanowire-loaded surface plasmon polariton waveguides: an alternative to the hybrid guiding scheme," Journal of Physics D: Applied Physics 46(44), 445105 (2013). “Front cover of the issue” (SCI:000326188100010, Impact Factor: 2.721) [Link] [PDF]
Nanowire-loaded surface plasmon polariton waveguide is an extremely simple structure that can be naturally formed by directly dropping a dielectric cylinder onto a metallic substrate. However, despite the substantial emphasis devoted to its hybrid plasmonic counterparts, this waveguiding structure has been paid little attention to so far. Here in this paper, through comprehensive numerical analysis, we reveal that such a configuration can be leveraged to achieve deep-subwavelength field confinement with mode area more than one order of magnitude smaller than that of the conventional hybrid waveguide, while maintaining a moderate attenuation with propagation distance over tens of microns. Two-dimensional parameter mapping concerning physical dimension, shape and material of the nanowire as well as the refractive index of the cladding has disclosed the wide-range existence nature of this plasmonic mode and the feasibility to further balance its confinement and loss.
33. Yusheng Bian, and Qihuang Gong, "Optical performance of one-dimensional hybrid metal-insulator-metal structures at telecom wavelength," Optics Communications 308, 30-35 (2013). “Most Downloaded Optics Communications Articles” (SCI:000328595900007, Impact Factor: 1.449) [Link] [PDF]
The guiding properties of a one-dimensional hybrid metal-insulator-metal (MIM) waveguiding structure that incorporates an additional high-index dielectric layer sandwiched between two low-index-dielectric-metallic walls are investigated numerically at the telecom wavelength. Compared with the conventional MIM waveguide, the hybrid MIM structure can achieve both lower propagation loss and enhanced optical confinement under careful design. 2D modal analysis combined with investigation on its transmission properties reveals that the crosstalk between adjacent waveguides can be significantly reduced by replacing the traditional MIM waveguides with their hybrid MIM counterparts. These investigations could offer useful guidelines for the design and optimization of hybrid plasmonic waveguides and components.
32. Yusheng Bian, and Qihuang Gong, "Low-loss light transport at the subwavelength scale in silicon nano-slot based symmetric hybrid plasmonic waveguiding schemes," Optics Express 21(20), 23907-23920 (2013). (SCI:000325549800086, Impact Factor: 3.488) [Link] [PDF]
A hybrid plasmonic structure comprising a silicon slot waveguide separated from an inverse metal ridge by a thin low-index insulator gap is proposed and investigated. Owing to its symmetric hybrid configuration containing closely spaced silicon rails near the metal ridge, the fundamental symmetric hybrid slot mode supported by the structure is demonstrated to be capable of simultaneously achieving low propagation loss and subwavelength field confinement within a wide range of physical dimensions at the telecom wavelength. Comprehensive numerical investigations regarding the effects of key geometric parameters on the guided modes' properties, including the slot sizes, the shape and dimension of the silicon rails, the width of the gap region as well as the height of metallic nanoridge, have been conducted. It is revealed that the propagation distance of the symmetric mode can be more than several millimeters (even up to the centimeter range), while simultaneously achieving a subwavelength mode size and tight field confinement inside the gap region. In addition to the studies on the modal characteristics, excitation strategies of the guided hybrid modes and the conversion between dielectric slot and hybrid slot modes are also numerically demonstrated. The studied platform potentially combines the advantages of silicon slot and plasmonic structures, which might lay important groundwork for future hybrid integrated photonic components and circuits.
31. Yusheng Bian, and Qihuang Gong, "Metallic Nanowire-Loaded Plasmonic Slot Waveguide for Highly Confined Light Transport at Telecom Wavelength," IEEE Journal of Quantum Electronics 49(10), 870-876 (2013). “Front cover of the issue” (SCI:000324746800003, Impact Factor: 1.887) [Link] [PDF]
The optical properties of a plasmonic slot waveguide that comprises a metallic nanowire supported by a thin-dielectric-coated metal surface are investigated at the telecom wavelength. The fundamental plasmonic mode sustained by the waveguiding configuration is shown to be strongly confined inside the gap between the nanowire and the metallic substrate, along with moderate propagation loss and deep-sub-wavelength mode size achievable simultaneously. Studies on the effects of key geometric parameters on the modal properties reveal that the tradeoff between confinement and loss could be well controlled through tuning the dimensions of the nanowire and the gap. Through conducting 3-D numerical simulations, we further show that its guided plasmonic mode can be directly excited using similar strategies to those of the TM0 plasmonic nanowire mode. The nice optical performance, in conjunction with significant field enhancement inside the nanoscale low-index gap region, could facilitate potential applications in sensing, nonlinear light processing, optical manipulation as well as the implementations of numerous ultra-compact passive, and active nanophotonic devices.
30. Yusheng Bian, Zheng Zheng, Jing Xiao, Haitao Liu, Jiansheng Liu, Jinsong Zhu, and Tao Zhou, "Gain-assisted light guiding at the nanoscale in a hybrid dielectric-loaded surface plasmon polariton waveguide based on a metal nanorod", Journal of Physics D: Applied Physics 46(33), 335102 (2013). (SCI:000322784200007, Impact Factor: 2.721) [Link] [PDF]
Hybrid dielectric-loaded plasmonic waveguide consisting of an inverted U-shaped high-index ridge covering atop a low-index polymer coated metal nanorod is proposed and numerically investigated. Through incorporating a gain medium either in the ridge or the buffer layer, the loss of the supported plasmonic mode can be effectively compensated. For a typical configuration comprising a 450 nm × 160 nm InGaAsP ridge with a 5–40 nm thick PMMA layer and a 30 nm wide Ag nanorod, the necessary gain required in InGaAsP for lossless propagation of the quasi-TE type symmetric hybrid mode can be as low as 3.45–9.85 cm−1, along with a subwavelength mode area (λ2/60–λ2/148) attainable simultaneously. The configuration potentially offers a promising solution to enable lossless light transport at the sub-diffraction-limited scale with low compensation gain, thereby opening venues for
ultra-compact active plasmonic devices and circuits.
ultra-compact active plasmonic devices and circuits.
29. Yusheng Bian, Zheng Zheng, Xin Zhao, Pengfei Yang, Jing Xiao, Jiansheng Liu, Jinsong Zhu, and Tao Zhou, "Silicon-Slot-Mediated Guiding of Plasmonic Modes: The Realization of Subwavelength Optical Confinement With Low Propagation Loss", IEEE Journal of Selected Topics in Quantum Electronics 20(4), 8100108 (2014). (SCI:000330317900013, Impact Factor: 2.828) [Link] [PDF]
Waveguiding platforms consisting of metallic nanowires embedded inside vertical-type dielectric slot waveguides are proposed and the guiding properties are investigated at the telecom wavelength. It is shown that the characteristics of the plasmonic modes can be strongly modified owing to the existence of the silicon rails in close proximity to the metallic nanowire, which enables low-loss light guiding with subdiffraction-limited mode area. Systematical analysis regarding the variation of key geometric parameters has revealed that the symmetric hybrid mode can existwithin a wide-range of physical dimensions, and demonstrates improved optical performance over either the conventional hybrid plasmonic mode or the fundamental plasmonicmode supported by a single metal nanowire. Furthermore, we show numerically that the supported symmetric and asymmetric modes can be separately excited through controlling the polarization state of the Gaussian beam that illuminated onto the nanowire tip. The presented hybrid waveguides naturally extend the capabilities of both the silicon slot and metal nanowire structures, which could facilitate a number of potential applications at the subwavelength scale.
28. Yusheng Bian, and Qihuang Gong, "Low-loss hybrid plasmonic modes guided by metal-coated dielectric wedges for subwavelength light confinement," Applied Optics 52(23), 5733-5741 (2013). “Front cover of the issue” (SCI:000323880400023 , Impact Factor: 1.784) [Link] [PDF]
The optical characteristics of a metal-coated dielectric wedge structure are investigated at a wavelength of 1550 nm. The effects of the metal/gap layers’ thicknesses, as well as the dimension of the dielectric wedge on the guided modes’ properties, are systematically analyzed. It is revealed that the characteristics of the fundamental quasi-TE and quasi-TM plasmonic modes supported by the configuration demonstrate similar trends against the variation of the metal layer thickness while exhibiting quite different behaviors with the change of the wedge size. By choosing appropriate physical dimensions, both modes could simultaneously achieve low modal loss and subwavelength field confinement, along with reasonablemodepower inside the low-index gap region. Investigations on the directional coupling between adjacent identical waveguides indicate that ultralow crosstalk can be enabled by the quasi-TE mode, with the coupling length more than two orders of magnitude larger than that achieved by the plasmonic mode in conventional hybrid counterparts. The presented metal-coated dielectric wedge structures can be employed as important building blocks for a number of integrated nanophotonic components, and could also enable numerous applications at the subwavelength scale.
27. Yusheng Bian, Zheng Zheng, Xin Zhao, Yalin Su, Lei Liu, Jiansheng Liu, Jinsong Zhu, and Tao Zhou, "Nanoscale light guiding in a silicon-based hybrid plasmonic waveguide that incorporates an inverse metal ridge", Physica Status Solidi A 210(7), 1424-1428 (2013) (SCI:000327699800027, Impact Factor: 1.616) [Link] [PDF]
A silicon-based hybrid plasmonic waveguide that comprises an inverse metal ridge sitting above a silicon-on-insulator
substrate with a nanometre-thick, low-index gap is proposed and its guiding mode properties are analyzed numerically at the wavelength of 1,550 nm. The strongly hybridized modes supported by the inverse metal ridge and the thin silicon layer provide an efficient scheme to store the optical field inside the nanoscale gap region with strong local field enhancement. Compared to the previously studied hybrid plasmonic waveguides based on the coupling between metal wedges or metal ridges with finite-wide high-index nanowires, the present hybrid waveguide leveraging inverse metallic wedge with infinite-wide silicon layer simplifies the fabrication process to a certain extent and avoids the lateral misalignment that is rather challenging to control in many other hybrid plasmonic waveguiding counterparts. Besides, the studied structure also shows the potential to further reduce the mode size of conventional hybrid waveguide based on flat metal substrate, thus making itself an attractive building block for compact photonic integrated components and circuits.
substrate with a nanometre-thick, low-index gap is proposed and its guiding mode properties are analyzed numerically at the wavelength of 1,550 nm. The strongly hybridized modes supported by the inverse metal ridge and the thin silicon layer provide an efficient scheme to store the optical field inside the nanoscale gap region with strong local field enhancement. Compared to the previously studied hybrid plasmonic waveguides based on the coupling between metal wedges or metal ridges with finite-wide high-index nanowires, the present hybrid waveguide leveraging inverse metallic wedge with infinite-wide silicon layer simplifies the fabrication process to a certain extent and avoids the lateral misalignment that is rather challenging to control in many other hybrid plasmonic waveguiding counterparts. Besides, the studied structure also shows the potential to further reduce the mode size of conventional hybrid waveguide based on flat metal substrate, thus making itself an attractive building block for compact photonic integrated components and circuits.
26. Yusheng Bian, Zheng Zheng, Xin Zhao, Lei Liu, Yalin Su, Jing Xiao, Jiansheng Liu, Jinsong Zhu, and Tao Zhou, "Dielectrics Covered Metal Nanowires and Nanotubes for Low-Loss Guiding of Subwavelength Plasmonic Modes", Journal of Lightwave Technology 31(12), 1973-1979 (2013). (SCI:000319459600013, Impact Factor: 2.965) [Link] [PDF]
Two types of surface plasmon polariton waveguides consisting of square metal nanowires or nanotubes covered by low-high index dielectric layers are presented and their guiding characteristics are investigated numerically at the telecom wavelength of 1550 nm. Numerical analysis reveals that depending on the sizes of the covered low-high index dielectric layers, the nanowire based waveguides can be tuned to provide subwavelength confinement of the plasmonic modes with low propagation loss. Even enhanced optical confinement could be achieved by further increasing the nanowire size or replacing the metal nanowires by nanotubes. Consideration of directional coupling between two identical such plasmonic waveguides reveal ultra-low-crosstalk can be realized with relatively small separation distances. These waveguiding structures, compatible with modern fabrication methods, potentially enable the realization of numerous ultra-compact integrated photonic components.
25. Yusheng Bian, Zheng Zheng, Xin Zhao, Lei Liu, Yalin Su, Jiansheng Liu, Jinsong Zhu, and Tao Zhou, "Modal properties of triangular metal groove/wedge based hybrid plasmonic structures for laser actions at deep-subwavelength scale", Optics Communications 297, 102-108 (2013). (SCI:000318135300018, Impact Factor: 1.449) [Link] [PDF]
Triangular metal groove/wedge based hybrid plasmonic structures are leveraged for nanolaser applications. It is shown through numerical simulations that by controlling the tip angle of the triangular metallic substrate, tunable lasing properties can be readily achieved. On the one hand, metal substrates with grooves could benefit enhanced optical confinement and meanwhile results in a reduced lasing threshold with carefully engineered tip angles. While on the other hand, metal wedge based structures could be used to further scale down the size of the stimulated optical mode, potentially enabling the realization of ultra-deep-subwavelength laser action. These novel structures could perform as efficient subwavelength light sources with flexible lasing properties, thereby facilitating diverse applications in future advanced active photonic systems.
24. Yusheng Bian, Zheng Zheng, Xin Zhao, Lei Liu, Yalin Su, Jiansheng Liu, Jinsong Zhu, and Tao Zhou, "Hybrid plasmon polariton guiding with tight mode confinement in a V-shaped metal/dielectric groove", Journal of Optics 15(5), 055011 (2013). (SCI:000319555500013, Impact Factor: 2.059) [Link] [PDF]
Plasmonic waveguides consisting of metallic grooves filled with low- and high-index dielectrics are proposed and the optical properties of guided plasmonic modes are investigated at a wavelength of 1550 nm. Numerical simulations reveal that the quasi-TE-like fundamental hybrid plasmonic mode exhibits strong localization near the low-index dielectric gap, along with pronounced local field enhancement and relatively small mode area. Moderate propagation loss can be achieved as well, corresponding to a propagation distance of around tens to hundreds of microns. The proposed hybrid plasmonic structure is compatible with the fabrication techniques of traditional channel plasmon polariton waveguides, and these structures could be employed as interesting building blocks for highly integrated photonic circuits.
23. Yusheng Bian, Zheng Zheng, Xin Zhao, Pengfei Yang, Lei Liu, Jiansheng Liu, Jinsong Zhu, and Tao Zhou, "Gain enhancement in a V-shaped plasmonic slot waveguide for efficient loss compensation at the subwavelength scale", Optics Communications 294, 414-419(2013). (SCI:000317633200070, Impact Factor: 1.449) [Link] [PDF]
An active plasmonic slot waveguide comprising an inverted triangular metal wedge incorporated inside a V-shaped plasmonic groove with a low-index gain medium embedded between them is presented, and its guiding properties are investigated numerically at the wavelength of 1550 nm. The presented waveguide is shown to be capable of supporting two fundamental plasmonic slot modes with high field localization to the V-shaped low-index slot region. Due to such strong optical confinement and significant field enhancement, the introduced gain in the slot could effectively compensate the propagation loss of the supported plasmonic modes. It is revealed that for the studied channel plasmonic slot and wedge plasmonic slot modes, notable gain enhancements are observable within a wide range of geometric parameters. For the considered structure with a 10 ~ 40 nm-wide slot, the enhancements of gain can be as large as 11 % ~ 159 % for the CPS mode while 43 % ~ 174 % for the WPS mode. These values could be further improved by adopting even narrower slots. It is shown that, by introducing a gain medium with coefficients around hundreds of cm-1, the modal loss can be largely or even fully compensated, with a subwavelength mode area achievable simultaneously. These unique features of the studied V-shaped plasmonic slot waveguide might be useful for its potential applications in compact, active plasmonic components.
22. Lei Liu, Zheng Zheng, Xin Zhao, Songsong Sun, Yusheng Bian, Yalin Su, Jiansheng Liu,Jinsong Zhu,"Dual-wavelength passively Q-switched Erbium doped fiber laser based on an SWNTsaturable absorber", Optics Communications 294, 267-270 (2013). (SCI:000317633200046, Impact Factor: 1.449) [Link] [PDF]
We report a dual-wavelength, all-fiber, passively Q-switched Erbium doped fiber laser based on a single-wall carbon nanotube saturable absorber. By just varying the pump power to balance the peaks of the Erbium doped fiber gain spectra in the cavity, the laser can operate in the dual-wavelength Q-switching regime without intracavity spectral filters or modulation elements. Our experimental results show that the fiber laser can simultaneously generate Q-switched microsecond pulses at ∼1532 nm and ∼1558 nm, which have the same repetition rate of tens of kHz and around 0.5 nJ pulse energies. Our scheme is quite simple to implement at a low cost.
21. Yusheng Bian, Zheng Zheng, Xin Zhao, Yalin Su, Lei Liu, Jiansheng Liu, Jinsong Zhu, and Tao Zhou, "Highly Confined Hybrid Plasmonic Modes Guided by Nanowire-embedded-metal Grooves for Low-loss Propagation at 1550nm", IEEE Journal of Selected Topics in Quantum Electronics 19(3), 4800106 (2013) (SCI:000322125100031, Impact Factor: 2.828) [Link] [PDF]
A waveguiding configuration consisting of a semiconductor nanowire embedded in a dielectric-coated V-shaped metal
groove is presented. The modal properties of the fundamental quasi-TE hybrid plasmonic mode are investigated at the wavelength of 1550 nm. Simulation results reveal that by tuning the size of the nanowire, the hybridization between the dielectric mode, and plasmonic mode could be effectively controlled. Through appropriate design, the hybridmode could be strongly localized in the nanowire and the gap regions on each side, featuring both tight mode confinement and low propagation loss. Besides, the compromise between confinement and loss could also be balanced by controlling the angle or depth of the metal groove. Moreover, it is found that the hybrid mode could exist for a wide geometrical parameter range, even when the corresponding metal groove by itself does not support a guided channel plasmon polariton mode. The proposed hybrid structure is technologically simple and compatible with planar fabrication methods while avoiding alignment errors.
groove is presented. The modal properties of the fundamental quasi-TE hybrid plasmonic mode are investigated at the wavelength of 1550 nm. Simulation results reveal that by tuning the size of the nanowire, the hybridization between the dielectric mode, and plasmonic mode could be effectively controlled. Through appropriate design, the hybridmode could be strongly localized in the nanowire and the gap regions on each side, featuring both tight mode confinement and low propagation loss. Besides, the compromise between confinement and loss could also be balanced by controlling the angle or depth of the metal groove. Moreover, it is found that the hybrid mode could exist for a wide geometrical parameter range, even when the corresponding metal groove by itself does not support a guided channel plasmon polariton mode. The proposed hybrid structure is technologically simple and compatible with planar fabrication methods while avoiding alignment errors.
20. Yuhang Wan, Zheng Zheng, Xiaogang Shi, Yusheng Bian, and Jiansheng Liu, "Hybrid plasmon waveguide leveraging Bloch surface polaritons for sub-wavelength confinement," Science China-Technological Sciences 56(3), 567-572 (2013). (SCI:000314913900007, Impact Factor: 1.192) [Link] [PDF]
A novel hybrid plasmonic waveguide based on a guided Bloch surface polariton structure is proposed and investigated. This hybrid waveguide overcomes the weak confinement in the Bloch surface polariton structure caused by the diffraction limitation. By introducing a metal stripe near the dielectric ridge located on the periodic multilayer structure that is designed to support a TM polarized Bloch surface polariton, a sub-wavelength scale electric field confinement is realized. The coupling of the Bloch surface polariton and the surface plasmon polariton results in a strong field distribution within the gap between the metal stripe and the dielectric ridge. The variation of the characteristic of the hybrid mode is revealed via tuning the height of the ridge and the coupling distance. Sub-wavelength scale mode size is realized as well as a propagation length of about 100 um.
19. Yusheng Bian, Zheng Zheng, Xin Zhao, Lei Liu, Yalin Su, Jiansheng Liu, Jinsong Zhu, and Tao Zhou, "Hybrid plasmonic waveguide incorporating an additional semiconductor stripe for enhanced optical confinement in the gap region", Journal of Optics 15(3), 035503 (2013). “Selected in‘Highlights of 2013’collection of Journal of Optics” (SCI:000315590700026, Impact Factor: 2.059) [Link] [PDF]
A hybrid plasmonic waveguide consisting of a thin high-index dielectric stripe embedded inside the gap between a metallic substrate and a semiconductor ridge is presented for the purpose of enhanced optical confinement in the gap. By engineering the key geometrical parameters of the stripe, both of the power ratios resided inside the whole gap and the silicon ridge can be enhanced greatly. A power confinement ratio as large as 0.54 in the overall gap region is achievable, for a structure with a 200 nm-wide, 90 nm-thick silicon-stripe embedded in the center of a 100 nm-thick silica gap, which is nearly 50% improvement over that of the corresponding conventional hybrid waveguide. Meanwhile, with the introduction of the 90 nm-thick silicon stripe, the effective mode area of the waveguide exhibits a reduction of
50%–60% with a reasonable propagation length around 25–65 m for different stripe widths. A study on the influence of possible fabrication imperfections reveals that the modal property is quite robust and highly tolerant to these errors. Such a hybrid plasmonic waveguide with enhanced optical confinement and moderate modal loss may enable the realization of ultra-compact passive components, nanolasers with low pumping thresholds, and other potential applications.
50%–60% with a reasonable propagation length around 25–65 m for different stripe widths. A study on the influence of possible fabrication imperfections reveals that the modal property is quite robust and highly tolerant to these errors. Such a hybrid plasmonic waveguide with enhanced optical confinement and moderate modal loss may enable the realization of ultra-compact passive components, nanolasers with low pumping thresholds, and other potential applications.
18. Yusheng Bian, Zheng Zheng, Xin Zhao, Lei Liu, Jiansheng Liu, Jinsong Zhu, and Tao Zhou, "Nanowire based hybrid plasmonic structures for low-threshold lasing at the subwavelength scale", Optics Communications 287, 245-249 (2012). (SCI:000312688300042, Impact Factor: 1.449) [Link] [PDF]
Novel plasmonic nanolaser structures are proposed by leveraging the efficient guiding properties of hybrid plasmonic modes of nanowire based waveguides. Theoretical investigations reveal that the coupling between the metal nanowire and the high-index dielectric nanostructure with optical gain results in strong field enhancement in the low-index gap region, sufficient modal overlap with the gain medium and low propagation loss, which could enable lasing at the subwavelength scale with low pump threshold. The proposed nanowire-based plasmonic nanolasers are also compatible with standard fabrication technology and could be appealing candidates for active photonic systems.
17. Yusheng Bian, Zheng Zheng, Xin Zhao, Yalin Su, Lei Liu, Jiansheng Liu, Jinsong Zhu, and Tao Zhou, "Hybrid plasmonic structures based on CdS nanotubes:A novel route to low threshold lasing on the nanocale", Journal of Physics D: Applied Physics 45(50), 505105 (2012). (SCI:000311833000008, Impact Factor: 2.721) [Link] [PDF]
Nanowires and nanotubes could become important building blocks in advanced photonic systems owing to their fascinating optoelectronic properties and high compatibility with versatile chemical synthetic methods. Many intriguing studies have been enabled by applying these nanostructures in the construction of various types of active and passive photonic components. Successful examples are the recent demonstration of semiconductor and plasmonic lasers based on CdS nanowires (Duan et al 2003 Nature 421 241–5, Oulton et al 2009 Nature 461 629–32, Ma et al 2010 Nature Mater. 10 110–13), which generate and deliver intense coherent light down to and even below the diffraction-limited scale. Here in this paper, by carrying out a numerical investigation of a novel hybrid plasmonic structure that consists of a CdS nanotube sitting above a metal substrate separated by a nanometric MgF2 layer, we show theoretically that nanotube-based plasmonic structures can also act as highly efficient lasing sources. Optical properties of such a laser configuration including modal behaviour and the lasing threshold is investigated with regard to the variation of key geometrical parameters. Simulation results reveal that the employment of a CdS nanotube may result in improved optical performance compared with the conventional CdS-nanowire-based plasmon laser. Reduced lasing threshold with mitigated modal loss can be achieved simultaneously under carefully engineered geometries. We also explore the feasibility of combining nanowire- and nanotube-based active and passive components for on-chip integrations. As a simple demonstration, monolithic integration of a CdS nanotube laser with a CdS-nanowire-based passive component is shown numerically on a single chip. We expect that these studies could lay the foundations for nanotube- and nanowire-based hybrid integrated photonic components and circuits.
16. Yusheng Bian, Zheng Zheng, Xin Zhao, Yalin Su, Lei Liu, Jiansheng Liu, Jinsong Zhu, and Tao Zhou, "T-shaped dielectric slot waveguides for efficient control of birefringence and polarization independent directional coupling", Optics Communications 285, 5118-5121 (2012). (SCI:000311196500065, Impact Factor: 1.449) [Link] [PDF]
A novel dielectric slot waveguide supporting strongly confined field in a T-shaped low-index slot region for both TE and TM polarizations is proposed and analyzed. Numerical simulations have demonstrated that quite different birefringent modal properties are achievable with tight optical confinement in the slot by tuning key geometrical parameters of the waveguide. Based on such a slot structure, the characteristics of directional couplers are investigated and the conditions for polarization independent coupling are also given. The presented T-shaped slot waveguide might be employed in integrated photonic systems as important building blocks enabling a number of potential applications.
15. Yalin Su, Zheng Zheng, Yusheng Bian, Lei Liu, Xin Zhao, Jiansheng Liu, Tao Zhou, Shize Guo, Wei Niu, Yulong Liu and Jinsong Zhu, "Metal-coated hollow nanowires for low-loss transportation of plasmonic modes with nanoscale mode confinement", Journal of Optics 14(9), 095501 (2012). (SCI:000308800200013, Impact Factor: 2.059) [Link] [PDF]
Two types of plasmonic waveguiding structures based on hollow dielectric nanowires are proposed and their modal properties are investigated numerically at a wavelength of 1550 nm. The first type of waveguide consists of a high-index hollow nanowire covered directly by a thin metallic film. Depending on the size of the hollow nanowire, such a waveguide could support a plasmonic mode with lower propagation loss than the metal-coated nanowire structures without a hollow core. To further reduce the propagation loss, a second type of waveguide is proposed, which includes an additional low-index silica buffer layer between the metal layer and the hollow nanowire. Simulations reveal that the additional low-index buffer could enable strong hybridization between the dielectric mode and the plasmonic mode, which leads to even lower propagation loss while maintaining nanoscale confinement similar to that of the first type of waveguide. Both of the proposed waveguides are feasible using modern fabrication methods and could facilitate potential applications in integrated photonic components and circuits.
14. Jing Xiao, Jiansheng Liu, Zheng Zheng, Yusheng Bian, Guanjun Wang, and Shuna Li, "Transmission Performance of a Low-loss Metal-insulator-semiconductor Plasmonic Phase-shifted Bragg Grating", Physica Status Solidi A 209(8), 1552-1556 (2012) (SCI:000307548600023, Impact Factor: 1.616) [Link] [PDF]
We propose a plasmonics phase-shift Bragg grating based on a metal–insulator–semiconductor structure in the wavelength range of 1400–1700 nm. The Bragg grating is formed by a periodic height variation of a semiconductor strip that is separated from a metal surface by a nanoscale insulator layer. Moreover, a phase-shift structure was introduced in the middle of the Bragg grating. Simulation results demonstrate that the proposed structure exhibits good filtering characteristics with a strong field enhancement. The proposed phase-shift Bragg grating could be used as an ultracompact filter and enable on-chip integration of photonic circuits.
13. Jing Xiao, Jiansheng Liu, Zheng Zheng, Yusheng Bian, Guanjun Wang, and Shuna Li, "Low-loss metal-insulator-semiconductor waveguide with an air core for on-chip integration", Optics Communications 17, 3604-3607 (2012). (SCI:000305854300004, Impact Factor: 1.449) [Link] [PDF]
In this paper, a novel metal-insulator-semiconductor waveguide with an air core in the insulator layer is proposed in order to improve the on-chip integration. Compared with the structure with homogeneous insulator, the introduced air core provides an additional degree of freedom for tuning the characteristics of the hybrid plasmonic mode. Simulation results demonstrate that the proposed structure exhibits better tradeoff between the mode confinement and the propagation length. The relatively low crosstalk between adjacent proposed waveguides could be achieved and the coupling efficiency between conventional silicon waveguide and the proposed structure maintain. The proposed waveguide could be used to build ultra-compact photonic components and enable on-chip integration of photonic circuits.
12. Yusheng Bian, Zheng Zheng, Xin Zhao, Yalin Su, Lei Liu, Jiansheng Liu, Jinsong Zhu, and Tao Zhou, "Guiding of long-range hybrid plasmon polariton in a coupled nanowire array at deep-subwavelength scale", IEEE Photonics Technology Letters 24(15), 1279-1281 (2012). (SCI:000305748400005, Impact Factor: 2.110) [Link] [PDF]
A novel type of hybrid plasmonic waveguiding structure that integrates semiconductor and metallic nanowires has been proposed and investigated at telecommunication wavelengths. Semiconductor nanowires symmetrically placed on both sides of a metallic nanowire provide an additional degree of freedom for tuning the characteristics of the plasmonic nanowire mode. Theoretical analysis reveals that at appropriate geometrical parameters, the symmetric hybrid plasmonic mode of the waveguide could achieve subwavelength mode confinement with ultra-long propagation distance (even exceeding the millimeter range). Such a hybrid plasmonic nanowire structure could facilitate ultra-strong light-matter interaction between semiconductor and metal materials, and enable important applications in nanolasers and nonlinear photonics.
11. Guanjun Wang, Jiansheng Liu, Zheng Zheng, Yi Yang, Jing Xiao, Shuna Li, and Yusheng Bian, "Fluidic sensor based on the side-opened and suspended dual-core fiber", Applied Optics 51(15), 3096-3103 (2012). (SCI:000304246400038, Impact Factor: 1.784) [Link] [PDF]
For accelerating the response and enhancing the sensitivity simultaneously, a novel fluidic sensor based on a side-opened and suspended dual-core fiber and dual-beam interference detection mechanism is first explored and analyzed here. The side opening ensures a fast response by allowing fluidic analyte to approach the fiber core laterally. The dual-beam Mach–Zehnder interferemetry provides a relative higher sensitivity. Calculation results show that a sensitivity of 2.1 × 10−6 refractive index unit (RIU) within a response time of 10 s could be achievable, which reflects its potential impact on constructing a fluid refractometer for fast-response and high-sensitivity detection. Moreover, the relationship of the sensing sensitivity and the detected dynamic range of this suspended dual-core fiber structure, polarization,
and the transmitting waveband are also analyzed.
and the transmitting waveband are also analyzed.
10. Yuhang Wan, Zheng Zheng, Weijing Kong, Xin Zhao, Ya Liu, Yusheng Bian, and Jiansheng Liu, "Nearly three orders of magnitude enhancement of Goos-Hanchen shift by exciting Bloch surface wave", Optics Express 20(8), 8998-9003 (2012) (SCI:000302855500077, Impact Factor: 3.488) [Link] [PDF]
Goos-Hanchen effect is experimentally studied when the Bloch surface wave is excited in the forbidden band of a one-dimensional photonic band-gap structure. By tuning the refractive index of the cladding covering the truncated photonic crystal structure, either a guided or a surface mode can be excited. In the latter case, strong enhancement of the Goos-Hanchen shift induced by the Bloch-surface-wave results in sub-millimeter shifts of the reflected beam position. Such giant Goos-Hanchen shift, ~750 times of the wavelength, could enable many intriguing applications that had been less than feasible to implement before.
9. Zhiyou Wang, Zheng Zheng, Kun Wang, Yalin Su, Lei Liu, Lusheng Song, Yusheng Bian, Rui Hou, Shaopeng Li, and Jinsong Zhu, "Sensitive voltage interrogation method using electro-optically tunable SPR sensors", Optics Express 19(27), 26651-26659 (2011). (SCI:000301151500079, Impact Factor: 3.48) [Link] [PDF]
A novel voltage interrogation method using electro-optically tunable waveguide-coupled surface plasmon resonance sensors is demonstrated. Before measurements, we use a bicell photodetector to detect the reflectance from the sensor and take the differential signal from the photodetector as the resonance condition. For different analytes, by scanning the DC voltage on the waveguide layer of the sensor chip, the resonance condition can be maintained the same. Under this condition, we record the values of this voltage, namely the resonant voltage. Theoretical calculations and experimental results show the resonant voltage has a highly linear and sensitive response to analyte’s refractive index. This method is simple in configuration, and complicated signal processing algorithms can be avoided.
8. Yusheng Bian, Zheng Zheng, Ya Liu, Jinsong Zhu, and Tao Zhou, "Hybrid wedge plasmon polariton waveguide with good fabrication-error-tolerance for ultra-deep-subwavelength mode confinement", Optics Express 19(23), 22417-22422 (2011). (SCI:000296904700021, Impact Factor: 3.488) [Link] [PDF]
A novel hybrid plasmonic waveguide consisting of a high-index dielectric nanowire placed above a triangular metal wedge substrate is proposed and analyzed theoretically. The strong coupling between the wedge plasmon polariton and the dielectric nanowire mode results in both the ultra-tight confinement and low propagation loss. Compared to the previous studied hybrid surface plasmon polariton structures without the metal wedge substrate, stronger field enhancement in the low-index gap region as well as improved figure of merit (FOM) could be realized simultaneously. Results of the modal properties considering certain fabrication imperfections show that the proposed structure is also quite tolerant to these errors.
7. Jing Xiao, Jiansheng Liu, Zheng Zheng, Yusheng Bian and Guanjun Wang, "Design and analysis of a nanostructure grating based on hybrid plasmonic slot waveguide", Journal of Optics 13(10), 105001 (2011). (SCI:000295932700001, Impact Factor: 2.059) [Link] [PDF]
A novel nanostructure grating with broadband reflection is proposed and analyzed in this paper. The grating is based on a hybrid plasmonic slot waveguide that consists of a vertical dielectric-slot incorporated at the gap between the upper silicon rib and the metal substrate. The structure could provide an ultra-tight mode confinement in the cross-section while maintaining a relatively low propagation loss. By exploiting the superior modal properties, an ultra-compact and broadband Bragg grating is presented, which shows the capability of efficient wavelength selection near the telecom bandwidths. The waveguide-based Bragg grating could be used as a filter in telecommunication systems and could be a promising candidate for future integrated photonic circuits.
6. Yuhang Wan, Zheng Zheng, Weijing Kong, Ya Liu, Zhiting Lu, and Yusheng Bian, " Direct experimental observation of giant Goos–Hänchen shifts from bandgap-enhanced total internal reflection", Optics Letters 36(18), 3539-3541 (2011). (SCI:000294951100003, Impact Factor: 3.292) [Link] [PDF]
Giant Goos–Hänchen (GH) shifts are experimentally demonstrated from a prism-coupled multilayer structure incorporating a one-dimensional photonic crystal (PC) through a bandgap-enhanced total internal reflection scheme. By combining the large phase changes near the bandgap of the PC and the low reflection loss of the total internal reflection, 2 orders of magnitude enhancement of the GH shift is realized with rather low extra optical loss, which might help to open the door toward many interesting applications for GH effects.
5. Yalin Su, Zheng Zheng, Yusheng Bian, Ya Liu, Jiansheng Liu, Jinsong Zhu, and Tao Zhou, "Low-loss silicon-based hybrid plasmonic waveguide with an air nanotrench for sub-wavelength mode confinement", Micro & Nano Letters 6(8), 643-645 (2011). (SCI:000294470400017, Impact Factor: 0.853) [Link] [PDF]
A hybrid plasmonic waveguide based on a silicon-on-insulator substrate with an air trench is proposed and investigated. Theoretical analysis demonstrates that the nano-scale air trench could result in strong local field enhancement and tight mode confinement. Besides, the transmission loss of the fundamental hybrid plasmonic mode could also be reduced despite the existence of the high-index silicon rib. The proposed structure is compatible with standard nanofabrication process based on the silicon wafers and could enable various nanophotonic integrated components.
4. Yusheng Bian, Zheng Zheng, Ya Liu, Jinsong Zhu, and Tao Zhou, "Coplanar plasmonic nanolasers based on edge-coupled hybrid plasmonic waveguides", IEEE Photonics Technology Letters 23(13), 884 - 886 (2011). (SCI:000291355000010, Impact Factor: 2.110) [Link] [PDF]
A novel type of coplanar plasmonic laser based on an edge-coupled hybrid plasmonic waveguide is proposed and analyzed theoretically. This structure enables the realization of an air gap between the nanowire and the metal layer that could facilitate enhanced field confinement. By simulating the modal properties and the lasing threshold under different geometric parameters, it is demonstrated that with smaller gap widths and metal films of a larger rounded-corner radius, the lasing threshold could be reduced significantly. The structure could enable deep-subwavelength lasing with low pump thresholds and be readily integrated with other plasmonic structures for future coplanar active plasmonic circuits.
3. Yusheng Bian, Zheng Zheng, Ya Liu, Jinsong Zhu, and Tao Zhou, "Dielectric-loaded surface plasmon polariton waveguide with a holey ridge for propagation-loss reduction and subwavelength mode confinement", Optics Express 18(23), 23756-23762 (2010). (SCI:000283940900044, Impact Factor: 3.488) [Link] [PDF]
A novel dielectric-loaded surface plasmon polariton (DLSPP) waveguide with an air nanohole within a high-index dielectric ridge is proposed and analyzed. It is demonstrated by simulations that the introduced air nanohole could strongly modify the modal behavior, and it could alleviate the transmission loss caused by the high-index ridge with rather small sacrifice in the mode area. Under certain geometric parameter ranges, a shallow and wide air nanohole at the metal surface could result in strong local field enhancement while improves the figure of merit (FOM). The proposed structure could enable the realization of the DLSPP waveguide with a high-index ridge to achieve subwavelength mode confinement with relatively low transmission loss.
2. Lin An, Zheng Zheng, Yusheng Bian, Zheng Li, Sen Shi, Tao Zhou and Jiangtao Cheng, "Dispersion-Modified, Highly-Nonlinear Holey Fibre with a High-Index, Slot-Structure Core", Journal of Optics 12(11), 115502 (2010). (SCI:000284830000016,Impact Factor: 2.059) [Link] [PDF]
The group velocity dispersion (GVD) characteristics of a holey fibre design with a high index, slot structure in the core region are modified by introducing a simple cladding structure with a few large air holes. Our simulation results show that ultra-small mode effective areas and a high nonlinearity of the TE mode can be achieved, which is confined in the narrow slot by two silicon slabs in a glass fibre. This slot structure can be optimized to simultaneously achieve a very small Aeff and a single-TE-mode propagation. On the other hand, the proposed cladding can significantly reduce and flatten the large negative GVD of the slot structure, which could improve the nonlinear efficiency and interaction length for nonlinear applications. Our results indicate that an ultra-small Aeff of 0.16 μm2 and a flattened and reduced GVD with less than 10 ps nm−1 km−1 dispersion ripple within a 40 nm range at the 1.55 mm wavelength are achievable.
1. Yusheng Bian, Zheng Zheng, Xin Zhao, Jinsong Zhu, and Tao Zhou, "Symmetric hybrid surface plasmon polariton waveguides for 3D photonic integration", Optics Express 17(23), 21320-21325 (2009). (SCI:000271630000081, Impact Factor: 3.488) [Link] [PDF]
A two-dimensional symmetric hybrid plasmonic waveguide that integrates two high-refractive-index dielectric slabs with a finite-width insulator-metal-insulator (IMI) structure is proposed, and the characteristics of its long-range propagation mode are numerically analyzed at 1550 nm wavelength. In contrast to the previously studied structures, the gap between the slabs and the metal stripe and the associated field enhancement effect result in the dramatically modified modal behavior. It is shown that, under optimized configurations, the transmission loss can be reduced significantly with little change in the mode confinement capability compared to similar dielectric-loaded surface plasmon polariton waveguides. Studies on the crosstalk between adjacent such hybrid waveguides reveal the ability to increase the integration density by ~60 times compared with the traditional IMI structures when used in 3D photonic circuits. The studied waveguide could be an interesting alternative to realize high density photonic circuits.