M. Karl

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

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.

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

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.

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

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.

High resolution imaging of few-layer graphene

In this work, we successfully demonstrate how imaging ellipsometry can be applied to obtain high-resolution thickness maps of few-layer graphene (FLG) samples, with the results being thoroughly validated in a comparative study using several complementary techniques: Optical reflection microscopy (ORM), atomic force microscopy (AFM), and scanning confocal Raman microscopy. The thickness map, revealing distinct terraces separated by steps corresponding to mono- and bilayers of graphene, is extracted from a pixel-to-pixel fitting of ellipsometric spectra using optical constants (n = 2.7 and k = 1.2) derived by fitting slab model calculations to averaged Ψ and Δ spectra collected in large homogenous sample areas. An analysis of reflection spectra and contrast images acquired by ORM confirm the results by quantifying the number of graphene layers and retrieving the FLG optical constants using a simple Fresnel-law-based slab model. The morphology results are further corroborated with AFM and Raman images, the l...

Silicon-on-Insulator Nanowire Resonators for Compact and Ultra-High Speed All-Optical Wavelength Converters

We present the development of application-specific silicon-on-insulator SOI nanowire ring and racetrack resonators designed to assist semiconductor optical amplifier (SOA)-based all-optical wavelength conversion. We demonstrate the fabrication of fix resonance racetrack resonators exhibiting coupling gaps as low as 160 nm and tunable ring resonators with coupling gaps <; 90 nm. The resonators are cascaded after commercial 40 Gb/s SOAs to realize chirp filtering of the optical data signals through high-resolution spectral sampling. We experimentally demonstrate inverted and non-inverted SOI resonator-assisted all-optical wavelength conversion at 40 Gb/s and 160 Gb/s with power penalties <; 3 dB.

Tb/s switching fabrics for optical interconnects using heterointegration of plasmonics and silicon photonics: The FP7 PLATON approach

We present recent work that is carried out within the FP7 project PLATON on novel Tb/s switch fabric architectures and technologies for optical interconnect applications, employing heterointegration of plasmonics, silicon photonics and electronics.

All-optical wavelength conversion at 160Gb/s using an SOA and a 3 rd order SOI nanowire periodic filter

We present 160Gb/s all-optical wavelength conversion using an SOA and a 3rd order racetrack resonator integrated on a SOI nanowire platform. The scheme requires 0.5W of electrical power and the power penalty is <;3 dB.

Design, fabrication, and characterisation of fully etched TM grating coupler for photonic integrated system-in-package

Grating couplers are the best solution for testing nano-photonic circuits. Their main benefit is that they allow access via an optical fiber from the top and therefore there is no need to dice the chip and prepare the facets crucially. In the PLATON project grating couplers were designed to couple TM mode into and out of the SOI waveguides. Simulations came up with a grating coupler layout capable of theoretical coupling losses lower than 3dB for 1550 nm in TM configuration. A fully etched grating structure was chosen for fabrication simplicity and the optimal filling factor was found. The structures were fabricated using proximity error correction (PEC) and show a uniform coupling efficiency for all couplers. Therefore they are well-suited for all applications which demand for stable fiber-to-chip coupling. The spectral response of the structures was measured from 1500 to 1580 nm with 2 nm step and measuring the fiber-tofiber losses of three straight waveguides equipped with three grating couplers with different gap widths. The optimal grating period exhibits adequate coupling losses of 3.23 dB per coupler at 1557 nm, being therefore the most promising design.