Dany-Sebastien Ly-Gagnon

Multiple-wavelength focusing of surface plasmons with a nonperiodic nanoslit coupler.

A novel type of multiple-wavelength focusing plasmonic coupler based on a nonperiodic nanoslit array is designed and experimentally demonstrated. An array of nanoslits patterned on a thin metal film is used to couple free-space light into surface plasmon polaritons (SPPs) and simultaneously focus different-wavelength SPPs into arbitrary predefined locations in the two-dimensional plane. We design and fabricate a compact triplexer on a glass substrate with an integrated silicon photodetector. The photocurrent spectra demonstrate that the incident light is effectively coupled to SPPs and routed into three different focal spots depending on the wavelength. The proposed scheme provides a simple method of building wavelength-division multiplexing and spectral filtering elements, integrated with other plasmonic and optoelectronic devices.

Routing and photodetection in subwavelength plasmonic slot waveguides

Abstract The ability to manipulate light at deeply sub-wavelength scales opens a broad range of research possibilities and practical applications. In this paper, we go beyond recent demonstrations of active photonic devices coupled to planar plasmonic waveguides and demonstrate a photodetector linked to a two conductor metallic slot waveguide that supports a mode with a minute cross-sectional area of ∼λ2/100. We demonstrate propagation lengths of ∼10λ (at 850 nm), routing around 90° bends and integrated detection with a metal-semiconductor-metal (MSM) photodetector. We show polarization selective excitation of the slot mode and measure its propagation characteristics by studying the Fabry-Perot oscillations in the photocurrent spectra from the waveguide-coupled detector. Our results demonstrate the practicality of transferring one of the most successful microwave and RF waveguide technologies to the optical domain, opening up many opportunities in areas such as biosensing, information storage and communication.

Characteristic Impedance Model for Plasmonic Metal Slot Waveguides

We investigate the transmission properties of a subwavelength plasmonic slot waveguide. We show that the transmission can be accurately calculated using the characteristic impedance of the propagating mode. Using such a model, we show that it is possible to design devices without extensive 3-D finite-difference time-domain (FDTD) computer simulations. We illustrate the approach with calculations of an asymmetric Fabry-Perot germanium photodetector based on the slot waveguide geometry, showing predicted detector efficiencies as high as 69% despite metallic losses.

Tensile-strained germanium-on-insulator substrate fabrication for silicon-compatible optoelectronics

We present a method to fabricate tensile-strained germanium-on-insulator (GOI) substrates using heteroepitaxy and layer transfer techniques. The motivation is to obtain a high-quality wafer-scale GOI platform suitable for silicon-compatible optoelectronic device fabrication. Crystal quality is assessed using X-Ray Diffraction (XRD) and Transmission Electron Microscopy. A biaxial tensile film strain of 0.16% is verified by XRD. Suitability for device manufacturing is demonstrated through fabrication and characterization of metal–semiconductor–metal photodetectors that exhibit photoresponse beyond 1.55 μm. The substrate fabrication process is compatible with complementary metal–oxide–semiconductor manufacturing and represents a potential route to wafer-scale integration of silicon-compatible optoelectronics.

Plasmonic Waveguides as Transmission Lines

We show that simple transmission line models can describe mode propagation in plasmonic waveguides. Despite different metal behavior at near-infrared compared to microwaves, our simulation results agree very well with our impedance model predictions.

B-CALM: An open-source GPU-based 3D-FDTD with multi-pole dispersion for plasmonics

Numerical calculations with finite-difference time-domain (FDTD) on metallic nanostructures in a broad optical spectrum require an accurate approximation of the permittivity of dispersive materials. Here, we present the algorithms behind B-CALM (Belgium-California Light Machine), an open-source 3D-FDTD solver operating on Graphical Processing Units (GPUs) with multi-pole dispersion models. Our modified architecture shows a reduction in computational times for multi-pole dispersion models for a broad spectral range. We benchmark B-CALM by computing the absorption efficiency of a metallic nanosphere with a one-pole and a three-poles Drude-Lorentz model and compare it with Mie theory.

Routing and detection of light on deeply subwavelength scale in two-conductor metallic slot waveguides

We demonstrate propagation, routing round bends and integrated detection of light on a deeply sub-wavelength scale in two-conductor metallic slot waveguides. Light with cross-section ~ λ2/100 propagates ~10λ at 850nm in good agreement with simulations.

B-CALM: an open-source GPU-based 3D-FDTD with multi-pole dispersion for plasmonics

Numerical calculations with finite-difference time-domain (FDTD) on metallic nanostructures in a broad optical spectrum require an accurate approximation of the permittivity of dispersive materials. Here, we present the algorithms behind B-CALM (Belgium-California Light Machine), an open-source 3D-FDTD solver operating on Graphical Processing Units (GPUs) with multi-pole dispersion models. Our modified architecture shows a reduction in computational times for multi-pole dispersion models for a broad spectral range. We benchmark B-CALM by computing the absorption efficiency of a metallic nanosphere with a one-pole and a three-poles Drude-Lorentz model and compare it with Mie theory.

Integrated Photodetectors in Metal Slot Plasmonic Waveguides

We developed a characteristic impedance model to investigate the transmission properties of plasmonic metal slot waveguides. We used this model to design photodetectors integrated in metal slot plasmonic waveguides.