Submicron-integrated plasmonic power splitter

A tunable power splitter based on metal-dielectric metal (MDM) waveguide coupled with rectangle cavity with Kerr nonlinear material is proposed. The power splitter properties are simulated by the finite-difference time-domain (FDTD) method [Y. H. Guo et al., Opt. Express 19 (2011) 13831–13838]. Simple theoretically analysis and numerically calculation demonstrate that the waveguide-rectangle cavity coupled system performs a tunable plasmonic power splitter. Additionally, the output power ratio can be efficiency tuned by varying the control light intensity. Results obtained by the coupled mode theory are consistent with those from the FDTD simulation. The plasmonic splitter may become a choice for the highly integrated optical circuits.

Multimode interference effect in plasmonic subwavelength waveguides and an ultra-compact power splitter

We present a simplified 2-D analytical subdomain model to predict the open-circuit magnetic field of a tubular linear permanent magnet oscillation generator (T-LPMOG) to account for its primary and secondary end effects. At present, the magnetic field calculations of the T-LPMOG are typically analyzed in cylindrical coordinates, and the end effect is neglected accordingly to apply the periodic boundary. In this paper, a simplified 2-D analytical subdomain model in polar coordinates is proposed to consider the end effect. First, a coordinate transformation method is adopted to establish the 2-D subdomain analytical model, the cylindrical coordinates are converted into polar coordinates, and the T-LPMOG is analyzed under this new coordinate system. Next, the subdomain method is used to analyze the analytical model by solving Laplace’s equation and the Poisson equation. Based on the simplified analytical model, the flux density and back-electromotive force are obtained. The analytical results are verified using the finite element analysis (FEA) method, and the computational times compared with the FEA method are provided. Finally, a T-LPMOG prototype is manufactured and tested, and the results show that the proposed analytical model can be useful in the initial design and optimization of the T-LPMOG.

The potential of graphene in plasmonic electro-optical waveguide modulators has been investigated in detail by finite-element method modelling of various widely used plasmonic waveguiding configurations. We estimated the maximum possible modulation depth values one can achieve with plasmonic devices operating at telecom wavelengths and exploiting the optical Pauli blocking effect in graphene. Conclusions and guidelines for optimization of modulation/intrinsic loss trade-off have been provided and generalized for any graphene-based plasmonic waveguide modulators, which should help in consideration and design of novel active-plasmonic devices.

We propose a wide-band power divider/combiner configuration to facilitate light access and manipulation in planar nano-plasmonic devices. Light is incident from a standard silicon nanowire (negligible propagation losses) to be accessed by a nano-plasmonic circuit providing subwavelength confinement. The structure circumvents the inherent losses associated with long distance light propagation in nano-plasmonic splitters as coupling and splitting are performed at the same interface with small splitting losses. Plasmonic slot waveguides (PSWs) are utilized for subwavelength confinement. Two PSWs placed orthogonally to a silicon nanowire are utilized for the power division/combining functionality. The power splitter has been analyzed by the finite-difference time-domain numerical method. The proposed device is of compact size and wide-band operation. The relative displacement of the silicon nanowire from the PSWs is optimized. A splitting of 34%, over most of the wavelength spectrum from 0.8-2.5 μm , is demonstrated.

Plasmonics-based waveguiding structures can deliver unprecedented degrees of wave-matter interaction, enhancing linear and nonlinear optical processes such as spectroscopy, sensing and signal processing, all within small form-factors and staggering device density. However, the main obstacle to a wider adoption has always been the excessive losses that scale poorly with optical confinement / localization [1-6]. Also in this work we demonstrate how can one utilize composite plasmonic waveguides with unparalleled alleviation of the loss-confinement tradeoff to achieve record Purcell factors within plasmonic waveguides [6]. Also I this talk we plan to discuss a novel class of nanoscale devices that address unmet performance demands for applications in data communications [1-6]. The performance of emerging generations of high-speed, integrated electronic circuits is increasingly dictated by interconnect density and latency as well as by power consumption. To alleviate these limitations, data communications using photons has been deployed, where photonic circuits and devices are integrated on platforms compatible with conventional electronic technologies. Within the dominant platform; namely Si, dielectric waveguides confine light via total internal reflection. This imposes bounds on minimizing device dimensions and density of integration. Those bounds arise due to the diffraction limit and the cross-coupling between neighbouring waveguides. Nanoscale Plasmonic waveguides provide the unique ability to confine light within a few nanometers and allow for near perfect transmission through sharp bends as well as efficient light distribution between orthogonally intersecting junctions. With these structures as a building block, new levels of optoelectronic integration and performance metrics for athermal transceivers with achievable bandwidths in excess of 500 Gbps as will be overviewed in this talk. In addition opportunities for the role that 2D materials may pay in propelling these record performance metrics even further will be projected [2]. 4.

Novel plasmonic power splitters constructed from a rectangular ring resonator with direct-connected input and output waveguides are presented and numerically investigated. An analytical model and systematic approach for obtaining the appropriate design parameters are developed by designing an equivalent lumped circuit model for the transmission lines and applying it to plasmonic waveguides. This approach can dramatically reduce simulation times required for determining the desired locations of the output waveguides. Three examples are shown, the 1 × 3, 1 × 4, and 1 × 5 equal-power splitters, with the design method being easily extended to any number of output ports.

In this paper we introduce a coupled system of two quantum bits residing at the interface of a heterostructure device. The structure encompasses a reference quantum bit, a photonic/plasmonic crystal waveguide and an obedient quantum bit. Each quantum bit is an electronic device which is designed based on an anti-dot lattice of two-dimensional electron gas in heterostructures. By applying a potential gate in the aforementioned structure it is possible to control electronic tunneling rate and hence quantum bits' swapping frequency. Coupling through the plasmonic waveguide may be employed to entangle quantum bits. The waveguide has been designed by exploiting conducting islands of two-dimensional electron gas in a host of layered semiconductor heterostructure, behaving effectively as a patterned metallic thin film. The plasmonic characteristic is here modeled by Drude dispersion which obviates the required frequency dependency of our case. Employment of a plasmonic crystal waveguide benefited from plasmonic nature instead of regular dielectrics decreases the dimensions ten-fold, which helps the structure's size to come within the range of practical fabrication technologies. In order to estimate the evolution of the entangled state of the pair of quantum bits, it is necessary to estimate the coupling coefficient between electronic and optical subsystems. This parameter can be regarded as a design goal of matched electronic and optical structures, and has been discussed in detail for the optimization purposes. In the present work, both plasmonic and electronic properties are investigated. For simulating different sections, revised guided mode expansion (RGME) and finite difference time domain (FDTD) methods are employed.

Subwavelength conductor-gap-silicon plasmonic waveguides along with compact S-bends and Y-splitters were theoretically investigated and experimentally demonstrated on a silicon-on-insulator platform. A thin SiO2 gap between the conductor layer and silicon core provides subwavelength confinement of light while a long propagation length of 40 microm was achieved. Coupling of light between the plasmonic and conventional silicon photonic waveguides was also demonstrated with a high efficiency of 80%. The compact sizes, low loss operation, efficient input/output coupling, combined with a CMOS-compatible fabrication process, make these conductor-gap-silicon plasmonic devices a promising platform for realizing densely-integrated plasmonic circuits.

In this paper, we propose a general boundary integral equation (BIE) approach for solving both exterior (e.g., scattering) and interior (e.g., guided wave propagation) problems involving general plasmonic waveguiding structures with arbitrary cross-sectional geometries and with a continuous translational symmetry in the direction of wave propagation. Contrary to the field-based approach which deals with the electric and magnetic fields, we employ a potential-based formalism instead, involving vector and scalar potentials, and match them at the media interfaces. The proposed approach can handle not only conventional plasmonic waveguides on the order of a few hundred nanometers but also those whose critical sizes are a few nanometers and in which the nonlocal hydrodynamic effects need to be accounted for. The BIEs describing the interaction of light with the plasmonic waveguide are solved by the method of moments (MoM) algorithm. Two illustrative examples, the first one of which deals with the scattering problem, while the second computes the dispersion diagram of a plasmonic cylinder, are considered for both local and nonlocal cases. An excellent agreement is observed between the numerical and theoretical results, with the latter being derived from the generalized Mie theory.

Nano-scale power splitters based on Si hybrid plasmonic waveguides are designed by utilizing the multimode interference (MMI) effect as well as Y-branch structure. A three-dimensional finite-difference time-domain method is used for simulating the light propagation and optimizing the structural parameters. The designed 1 × 2 50:50 MMI power splitter has a nano-scale size of only 650 nm × 530 nm. The designed Y-branch power splitter is also very small, i.e., about 900 nm × 600 nm. The fabrication tolerance is also analyzed and it is shown that the tolerance of the waveguide width is much larger than±50 nm. The power splitter has a very broad band of over 500 nm. In order to achieve a variable power splitting ratio, a 2×2 two-mode interference coupler and an asymmetric Y-branch are used and the corresponding power splitting ratio can be tuned in the range of 97.1%:2.9%-1.7%:98.3% and 84%:16%-16%:84%, respectively. Finally a 1×4 power splitter with a device footprint of 1.9 μm × 2.6 μm is also presented using cascaded Y-branches.

Silicon photonics (SiPh) are considered a promising technology for increasing interconnect speed and capacity while decreasing power consumption. Mode division multiplexing (MDM) enables signals to be transmitted in different orthogonal modes in a single waveguide core. Wideband MDM components simultaneously supporting wavelength division multiplexing (WDM) and orthogonal frequency-division multiplexing (OFDM) can significantly increase the transmission capacity for optical interconnects. In this work, we propose, fabricate and demonstrate a wideband and channel switchable MDM optical power divider on an SOI platform, supporting single, dual and triple modes. The switchable MDM power divider consists of two parts. The first part is a cascaded Mach–Zehnder interferometer (MZI) for switching the data from their original TE0, TE1 and TE2 modes to different modes among themselves. After the target modes are identified, mode up-conversion and Y-branch are utilized in the second part for the MDM power division. Here, 48 WDM wavelength channels carrying OFDM data are successfully switched and power divided. An aggregated capacity of 7.682 Tbit/s is achieved, satisfying the pre-forward error correction (pre-FEC) threshold (bit-error-rate, BER = 3.8 × 10−3). Although up to three MDM modes are presented in the proof-of-concept demonstration here, the proposed scheme can be scaled to higher order modes operation.

In this paper, a controllable hybrid plasmonic integrated circuit (CHPIC) composed of hybrid plasmonic waveguide (HPW)-based rhombic nano-antenna, polarization beam splitter, coupler, filter, and sensor has been designed and investigated for the first time. In order to control the power into a corresponding input port, a graphene-based 1 × 3 power splitter with switchable output has been exploited. The functionality of each device has been studied comprehensively based on the finite element method and the advantages over state-of-the-art have been compared. Moreover, the effect of connection of CHPIC to the photonic and plasmonic waveguides has been studied to exhibit the capability of variety excitation methods of the CHPIC. Furthermore, the performance of the proposed CHPIC connected to inter/intra wireless transmission links has been investigated. The wireless transmission link consists of two HPW-based nano-antennas as transmitter and receiver with the maximum gain and directivity of 10 dB and 10.2 dBi, respectively, at 193.5 THz. The suggested CHPIC can be used for applications such as optical wireless communication and inter/intra-chip optical interconnects.

The triangular shape based hybrid metal-insulator-metal plasmonic waveguide, to achieve the low propagation loss at deep-subwavelength, has been proposed, and analyzed for the optical properties of the fundamental mode, such as normalized effective mode area, propagation length, etc., at <inline-formula><tex-math notation="LaTeX">$1550{\rm{\ nm}}$</tex-math></inline-formula> of working wavelength. Due to the triangular type of high-index regions, the light is primarily confined at its tip-points, i.e., within the low-index materials. This type of waveguide structure can essentially provide the remarkably low propagation loss at deep subwavelength. The optical performance of fundamental hybrid mode is analyzed, by altering the waveguide dimensions, including the angle of triangular-shape high-index layer. Further, the investigation of mode character helps to understand the mode behavior of the proposed waveguide. The simulation results have established that the propagation length of fundamental hybrid mode of the presented waveguide can be achieved as &#x223C; 279.7 &#x03BC;m, with the normalized effective mode area of <inline-formula><tex-math notation="LaTeX">$\sim \ 0.4842$</tex-math></inline-formula>, at <inline-formula><tex-math notation="LaTeX">$w= 200\ nm$</tex-math></inline-formula>, <inline-formula><tex-math notation="LaTeX">${h_{si}} = \ 300\ nm$</tex-math></inline-formula>, <inline-formula><tex-math notation="LaTeX">${h_g} = \ 10\ nm$</tex-math></inline-formula>, and <inline-formula><tex-math notation="LaTeX">${h_m} = \ 100\ nm$</tex-math></inline-formula>; however, with other waveguide dimensions, <inline-formula><tex-math notation="LaTeX">${L_p}$</tex-math></inline-formula> has been achieved as, <inline-formula><tex-math notation="LaTeX">$ &gt; 700\ \mu m.$</tex-math></inline-formula> Further, the analysis on coupling length <inline-formula><tex-math notation="LaTeX">$( {{L_c}} ),$</tex-math></inline-formula> between the two nearby and similar type of the proposed waveguides, have been accomplished, and <inline-formula><tex-math notation="LaTeX">${L_c} &gt; 2500\ \mu m$</tex-math></inline-formula> has been attained for the waveguide separation, and width respectively of <inline-formula><tex-math notation="LaTeX">$800\ nm$</tex-math></inline-formula>, and <inline-formula><tex-math notation="LaTeX">$200\ nm$</tex-math></inline-formula>. Moreover, the phases of fabrication process, along with the tolerance issues in fabricating the tip-points of high-index regions, have been discussed for the proposed waveguide structure. The waveguide structure proposed in this work can be fundamentally effective for the proposal of various nano-photonic components, such as power splitter, directional coupler, etc.

Silicon nitride waveguides provide low propagation loss but weak mode confinement due to the relatively small refractive index contrast between the Si₃N₄ core and the SiO2 cladding. On the other hand, metal-insulator-metal (MIM) plasmonic waveguides offer strong mode confinement but large propagation loss. In this work, MIM-like plasmonic waveguides and passive devices based on horizontal Cu-Si₃N₄-Cu or Cu-SiO₂-Si₃N₄-SiO₂-Cu structures are integrated in the conventional Si₃N₄ waveguide circuits using standard CMOS backend processes, and are characterized around 1550-nm telecom wavelengths using the conventional fiber-waveguide-fiber method. The Cu-Si₃N₄(~100 nm)-Cu devices exhibit ~0.78-dB/μm propagation loss for straight waveguides, ~38% coupling efficiency with the conventional 1-μm-wide Si₃N₄ waveguide through a 2-μm-long taper coupler, ~0.2-dB bending loss for sharp 90° bends, and ~0.1-dB excess loss for ultracompact 1 × 2 and 1 × 4 power splitters. Inserting a ~10-nm SiO₂ layer between the Si3N4 core and the Cu cover (i.e., the Cu-SiO2(~10 nm)-Si₃N₄(~100 nm)-SiO2(~10 nm)-Cu devices), the propagation loss and the coupling efficiency are improved to ~0.37 dB/μm and ~52% while the bending loss and the excess loss are degraded to ~3.2 dB and ~2.1 dB, respectively. These experimental results are roughly consistent with the numerical simulation results after taking the influence of possible imperfect fabrication into account. Ultracompact plasmonic ring resonators with 1-μm radius are demonstrated with an extinction ratio of ~18 dB and a quality factor of ~84, close to the theoretical prediction.