Electro-Optical Modulation Based on Pockels Effect in BaTiO3 With a Multi-Domain Structure

[EN] The influence of an in-plane multi-domain structure in BaTiO3 films grown on SrTiO3/Si buffers for highly efficient electro-optic modulation has been analyzed. The modulation performance can be significantly enhanced by rotating a certain angle, the optical waveguide, with respect to the BaTiO3 crystallographic axes. A robust electro-optical performance against variations in the domain structure as well as the lowest V-pi voltage can be achieved by using the rotation angles between 35 degrees and 55 degrees. Our calculations show that Vp voltages below 1.7 V for a modulation length of 2 mm can be obtained by means of a CMOS compatible hybrid silicon/BaTiO3 waveguide structure.This work was supported by the European Commission under Grant FP7-ICT-2013-11-619456 SITOGA. The work of P. Sanchis was supported in part by GVA under Grant PROMETEOII/2014/034 and in part by the Ministerio de Economia y Competitividad under Grant TEC2012-38540 LEOMIS.Castera, P.; Gutiérrez Campo, AM.; Tulli, D.; Cueff, S.; Orobtchouk, R.; Rojo Romeo, P.; Saint-Girons, G.... (2016). Electro-Optical Modulation Based on Pockels Effect in BaTiO3 With a Multi-Domain Structure. IEEE Photonics Technology Letters. 28(9):990-993. https://doi.org/10.1109/LPT.2016.252250999099328

Low-Loss and Compact Silicon Rib Waveguide Bends

[EN] Waveguide bends support intrinsically leaky propagation modes due to unavoidable radiation losses. It is known that the losses of deep-etched/strip waveguide bends increase inevitably for decreasing radius. Here, we theoretically and experimentally demonstrate that this result is not directly applicable to shallow-etched/rib waveguide bends. Indeed, we show that the total losses caused by the bends reach a local minimum value for a certain range of compact radii and rib waveguide dimensions. Specifically, we predicted the minimum intrinsic losses < 0.1 dB/90 degrees turn within the range of 25-30 mu m bend radii in a 220 nm-thick and 400 nm-wide silicon rib waveguide with 70 nm etching depth. This unexpected outcome, confirmed by experimental evidence, is due to the opposite evolution of radiation (bending) losses and losses caused by the coupling to lateral slab modes (slab leakage) as a function of the bend radius, hence creating an optimum loss region. This result may have important implications for the design of compact and low-loss silicon nanophotonic devices.This work was supported in part by the European STREP Program under Grant FP7-ICT-2013-11-619456-SITOGA and Grant FP7-ICT-2012-10-318240 PhoxTroT and in part by LEOMIS under Grant TEC2012-38540. (Corresponding author: Regis Orobtchouk.)Brimont, ACJ.; Hu, X.; Cueff, S.; Rojo-Romeo, P.; Saint Girons, G.; Griol Barres, A.; Zanzi, A.... (2016). Low-Loss and Compact Silicon Rib Waveguide Bends. IEEE Photonics Technology Letters. 28(3):299-302. https://doi.org/10.1109/LPT.2015.2495230S29930228

Formation of 300 nm period pore arrays by laser interference lithography and electrochemical etching

International audienceThis paper highlights that combining laser interference lithography and electrochemical etching is a cost-effective, efficient method to realize periodic nanopore arrays in silicon with lattice pitch as small as 300 nm on centimeter-scale substrates. The fabrication of wide-area and high aspect ratio 2D pore arrays with 250 nm diameter and 5 mu m depth is demonstrated. All the steps of the process have been optimized to achieve vertical sidewalls with 50 nm thickness, providing pore arrays with aspect ratio of 100 on n-type silicon substrates over an area of 2 x 2 cm(2). These results constitute a technological advance in the realization of ordered pore arrays in silicon with very small lattice parameters, with impact in biotechnology, energy harvesting, or sensors. (C) 2015 AIP Publishing LLC

Broad-band Source for Optical Gas Sensing at 5.6 -5.9 µm

21-25 june 2015International audienceno abstrac

Modeling the anisotropic electro-optic interaction in hybrid silicon-ferroelectric optical modulator

International audienceWe present a numerical method to accurately model the electrooptic interaction in anisotropic materials. Specifically, we combine a fullvectorial finite-difference optical mode solver with a radio-frequency solver to analyze the overlap between optical modes and applied electric field. This technique enables a comprehensive understanding on how electrooptic effects modify individual elements in the permittivity tensor of a material. We demonstrate the interest of this approach by designing a modulator that leverages the Pockels effect in a hybrid silicon-BaTiO3 slot waveguide. Optimized optical confinement in the active BaTiO3 layer as well as design of travelling-wave index-matched electrodes is presented. Most importantly, we show that the overall electro-optic modulation is largely governed by off-diagonal elements in the permittivity tensor. As most of active electro-optic materials are anisotropic, this method paves the way to better understand the physics of electro-optic effects and to improve optical modulators. (C) 2015 Optical Society of Americ

High-efficiency light coupling in a submicrometric silicon-on-insulator waveguide

International audienceLight coupling into a sub-micrometer-thick waveguide is usually done through a grating coupler. Coupling efficiency is strongly enhanced by addition of a mirror above the grating. This new kind of coupler can be designed to achieve efficiencies as great as 80%. Numerical calculations for a high-angular-spread Gaussian incident beam are compared with experimental results obtained for a standard silicon-on-insulator waveguide

How to determine the complex refractive index from infrared reflectance spectroscopy?

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Design and Fabrication of a Ring-Coupled Mach-Zehnder Interferometer Gyroscope

International audienceIn this paper, we present a CMOScompatible integrated photonics resonant gyroscope incorporating active Si&Ge components with low-loss SiN waveguiding structures for the first time. The gyroscope design is based on a ring-coupled Mach-Zehnder interferometer (19.2 mm ring length). Based on numerical modelling, the estimated resolution is 1.08 deg/s, representing a 1.56-times improvement over a single ring all-pass design with the same footprint. Further improvement afforded by the MZI-based design is expected under Kerr effet limited conditions. Devices were fabricated with the STMicroelectronics DAPHNE (Datacom Advanced Photonics Nanoscale Environment) 300 mm Photonic R&D platform. Experimental measurements under static (nonrotating) conditions confirm the numerical modelling results