Odysseas Tsilipakos

Theoretical analysis of thermally tunable microring resonator filters made of dielectric-loaded plasmonic waveguides

Microring resonator filters, which are made of dielectric-loaded surface plasmon polariton waveguides and operate in the telecom spectral range, are thoroughly analyzed by means of vectorial three dimensional (3D) finite element method (FEM) simulations. The filters’ functional characteristics, such as the resonant frequencies where the transmission minima occur, the free spectral range, the extinction ratio, and the minima linewidth associated with the quality factor of the resonances, are investigated for different values of the key structural parameters, namely, the ring radius and the gap separating the bus waveguide from the ring. The rigorous 3D-FEM simulations are qualitatively complemented by a simplified model. Apart from the harmonic propagation simulations, the uncoupled microring is treated as an eigenvalue problem, and the frequencies of the resonances are compared with those of the transmission minima. Furthermore, the possibility of exploiting the thermally tuned microring resonator filter ...

Thermo-optic plasmo-photonic mode interference switches based on dielectric loaded waveguides

We demonstrate an efficient thermo-optic dielectric loaded surface plasmon polariton waveguide (DLSPPW) 2 × 2 switch using a high thermo-optic coefficient polymer and a dual mode interference configuration. Unlike previous configurations relying on single-mode waveguide circuitry, the switch we consider is based on the interference between a plasmonic and a low-damping photonic mode of the DLSPPW, thus leading to the minimization of insertion losses of the device. Switching extinction ratios of 7 dB are measured for a compact 119 μm-long device. The overall device performances are in good agreement with numerical simulations performed using the beam propagation method.

A 320 Gb/s-Throughput Capable 2

We demonstrate a 2 × 2 silicon-plasmonic router architecture with 320 Gb/s throughput capabilities for optical interconnect applications. The proposed router platform relies on a novel dual-ring Dielectric-Loaded Surface Plasmon Polariton (DLSPP) 2 × 2 switch heterointegrated on a Silicon-on-Insulator (SOI) photonic motherboard that is responsible for traffic multiplexing and header processing functionalities. We present experimental results of a Poly-methyl-methacrylate (PMMA)-loaded dual-resonator DLSPP waveguide structure that uses two racetrack resonators of 5.5 μm radius and 4 μ m-long straight sections and operates as a passive add/drop filtering element. We derive its frequency-domain transfer function, confirm its add/drop experimental spectral response, and proceed to a circuit-level model for dual-ring DLSPP designs supporting 2 × 2 thermo-optic switch operation. The validity of our circuit-level modeled 2 × 2 thermo-optic switch is verified by means of respective full vectorial three-dimensional Finite Element Method (3D-FEM) simulations. The router setup is completed by means of two 4 × 1 SOI multiplexing circuits, each one employing four cascaded second order micro-ring configurations with 100 GHz spaced resonances. Successful interconnection between the DLSPP switching matrix and the SOI circuitry is performed through a butt-coupling design that, as shown via 3D-FEM analysis, allows for small coupling losses of as low as 2.6 dB. The final router architecture is evaluated through a co-operative simulation environment, demonstrating successful 2 × 2 routing for two incoming 4-wavelength Non-Return-to-Zero (NRZ) optical packet streams with 40 Gb/s line-rates.

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A comprehensive theoretical analysis of end-fire coupling between dielectric-loaded surface plasmon polariton and rib/wire silicon-on-insulator (SOI) waveguides is presented. Simulations are based on the 3-D vector finite element method. The geometrical parameters of the interface are varied in order to identify the ones leading to optimum performance, i.e., maximum coupling efficiency. Fabrication tolerances about the optimum parameter values are also assessed. In addition, the effect of a longitudinal metallic stripe gap on coupling efficiency is quantified, since such gaps have been observed in fabricated structures. Finally, theoretical results are compared against insertion loss measurements, carried out for two distinct sets of samples comprising rib and wire SOI waveguides, respectively.

2 Silicon-Plasmonic Router Architecture for Optical Interconnects

Thermo-optic switching elements made of dielectric-loaded plasmonic (DLSPP) waveguides are theoretically investigated by utilizing the three-dimensional vector finite element method. The configurations considered employ microring resonators, whose resonant frequency is varied by means of thermal tuning. First, a classic add-drop filter with parallel access waveguides is examined. Such a component features very poor drop port extinction ratio (ER). We therefore extend the analysis to add-drop filters with perpendicular access waveguides, which are found to exhibit superior drop port ERs, due to interference effects associated with the drop port transmission. In the process, the performance of a DLSPP waveguide crossing is also assessed, since it is a building block of those filters whose bus waveguides intersect. An elliptic tapering scheme is proposed for minimizing cross talk and its effect on the filter performance is explored. The dual-resonator add-drop filter with perpendicular bus waveguides and an ...

Interfacing Dielectric-Loaded Plasmonic and Silicon Photonic Waveguides: Theoretical Analysis and Experimental Demonstration

We demonstrate experimental evidence of the data capture and the low-energy thermo-optic tuning credentials of dielectric-loaded plasmonic structures integrated on a silicon chip. We show 7-nm thermo-optical tuning of a plasmonic racetrack-resonator with less than 3.3 mW required electrical power and verify error-free 10-Gb/s transmission through a 60-μm-long dielectric-loaded plasmonic waveguide.

Thermo-optic microring resonator switching elements made of dielectric-loaded plasmonic waveguides

We demonstrate Wavelength Division Multiplexed (WDM)-enabled transmission of 480Gb/s aggregate data traffic (12x40Gb/s) as well as high-quality 1x2 thermo-optic tuning in Dielectric-Loaded Surface Plasmon Polariton Waveguides (DLSPPWs). The WDM transmission characteristics have been verified through BER measurements by exploiting the heterointegration of a 60 μm-long straight DLSPPW on a Silicon-on-Insulator waveguide platform, showing error-free performance for six out of the twelve channels. High-quality thermo-optic tuning has been achieved by utilizing Cycloaliphatic-Acrylate-Polymer as an efficient thermo-optic polymer loading employed in a dual-resonator DLSPPW switching structure, yielding a 9 nm wavelength shift and extinction ratio values higher than 10 dB at both output ports when heated to 90°C.

Data Transmission and Thermo-Optic Tuning Performance of Dielectric-Loaded Plasmonic Structures Hetero-Integrated on a Silicon Chip

Spectral filtering and electromagnetically induced transparency (EIT) with hybrid silicon-plasmonic traveling-wave resonators are theoretically investigated. The rigorous three-dimensional vector finite element method simulations are complemented with temporal coupled mode theory. We show that ring and disk resonators with sub-micron radii can efficiently filter the lightwave with minimal insertion loss and high quality factors (Q). It is shown that disk resonators feature reduced radiation losses and are thus advantageous. They exhibit unloaded quality factors as high as 1000 in the telecom spectral range, resulting in all-pass filtering components with sharp resonances. By cascading two slightly detuned resonators and providing an additional route for resonator interaction (i.e., a second bus waveguide), a response reminiscent of EIT is observed. The EIT transmission peak can be shaped by means of resonator detuning and interelement separation. Importantly, the respective Q can become higher than that o...

0.48Tb/s (12x40Gb/s) WDM transmission and high-quality thermo-optic switching in dielectric loaded plasmonics

We present a thorough investigation of the electromagnetic resonant modes supported by systems of polaritonic rods placed at the vertices of canonical polygons. The study is conducted with rigorous finite-element eigenvalue simulations. To provide physical insight, the simulations are complemented with coupled mode theory (the analog of LCAO in molecular and solid state physics) and a lumped wire model capturing the coupling-caused reorganizations of the currents in each rod. The systems of rods, which form all-dielectric cyclic metamolecules, are found to support the unconventional toroidal dipole mode, consisting of the magnetic dipole mode in each rod. Besides the toroidal modes, the spectrally adjacent collective modes are identified. The evolution of all resonant frequencies with rod separation is examined. They are found to oscillate about the single-rod magnetic dipole resonance, a feature attributed to the leaky nature of the constituent modes. Importantly, we observe that ensembles of an odd number of rods produce larger frequency separation between the toroidal mode and its neighbor than the ones with even number of rods. This increased spectral isolation, along with the low quality factor exhibited by the toroidal mode, favors the coupling of the commonly silent toroidal dipole to the outside world, rendering the proposed structure a prime candidate for controlling the observation of toroidal excitations and their interaction with the usually present electric dipole

Electromagnetically induced transparency with hybrid silicon-plasmonic traveling-wave resonators

A side-coupled disk-waveguide system based on a long-range hybrid plasmonic waveguiding configuration is theoretically investigated for Kerr bistability and self-pulsation. The nonlinear response is studied with a theoretical framework combining perturbation theory and temporal coupled-mode theory, where all relevant effects, including two-photon absorption (TPA) as well as free-carrier dispersion (FCD) and absorption (FCA), are taken into account. We show that bistable operation with input powers as low as 40 mW is possible; a consequence of the significant reduction in resistive losses made possible by the long-range waveguiding principle. The effect of TPA, FCD, and FCA on the nonlinear response is thoroughly assessed and it is shown that carrier lifetime must drop to 8 ps in order to suppress free-carrier effects and obtain a high-quality bistable response, which is subsequently exploited for demonstrating ultrafast memory operation with low power requirements and high extinction ratio between states. Finally, by appropriate tuning of the carrier lifetime, FCD can lead to self-pulsation. The operating regimes in the detuning-power space are identified and the characteristics of the spontaneous oscillation discussed.