New concepts of integrated photonic biosensors based on porous silicon

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Phase Errors in mid-IR Arrayed Waveguide Gratings based on graded index SiGe-Si technology

In this paper, we present a method for analysis of phase errors and power truncation in SiGe/Si graded index arrayed waveguide gratings (AWGs) operating in mid-infrared spectral range. Semi-analytical model used herein is based on Gaussian approximation of the modal field and Fourier Optics. This method is applied to study the correlation between crosstalk level, effective index deviation in array waveguides and power truncation in 3.4 micrometer, 4.5 micrometer, 5.7 micrometer and 7.6 micrometer central wavelength AWGs. We show that the impact of effective index variation is more critical for AWGs with smaller operational wavelengths and power truncation should not exceed 5% for these types of devices. In conclusion, we refer to experimental data of 4.5 {\mu}m, 5.7 {\mu}m and 7.6 {\mu}m central wavelength AWGs where a cross talk level of 24 dB is obtained, corresponding to relative errors of effective indices and equivalent path length deviations respectively lower than 2 10-5 and of 0.2 micrometer in 10 mm length of the devices

Binary coded patterns for photon control using necklace problem concept

International audiencePseudo-disordered structures enable additional design freedom for photon management. However, the optimization and interpretation is challenging when the large number of degrees of freedom encounters computationally intensive electromagnetic simulation method. Here we propose a novel one-dimensional multi-periodic pattern generation method to help us squeeze the disorder design space before performing rigorous calculation, by making use of the periodic attribute of the pattern. Consequently, thanks to the pre-filtered design space, it typically relieves us from computational burden and enables us to ‘globally’ optimize and study pseudo-disordered patterns. As an example, we show how this approach can be used to comprehensively optimize and systematically analyze generated disorder for broadband light trapping in thin film

Morphological Effects in Photonic Integrated Nanojet

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Design rules for net absorption enhancement in pseudo-disordered photonic crystal for thin film solar cells

International audienceThe role of pseudo-disordered photonic crystals on the absorption efficiency of simplified thin film crystalline silicon solar cells is presented and discussed. The expected short circuit current can thus be further increased compared to a fully optimized square lattice of holes, thanks to carefully controlled positions of the nanoholes in the considered realistic simplified solar cell stack. In addition, the pseudo-disordered structures are less sensitive to the angle of incidence, especially in the long wavelength range

Scanning near-field optical microscopy as a tool for the characterization of multimode interference devices

International audienceWe report the scanning near-field optical microscopy (SNOM) characterization of a 4×4 multimode interference (MMI) device working at a wavelength of 1.55 μm and designed for astronomical signal recombination. A comprehensive analysis of the mapped propagating field is presented. We compare SNOM measurements with beam-propagation-method simulations and thus are able to determine the MMI structure's refractive-index contrast and show that the measured value is higher than the expected value. Further investigation allows us to demonstrate that good care must be taken with the refractive-index profile used in simulation when one deals with low-index contrast structures. We show evidence that a step-index contrast is not suitable for adequate simulation of our structure and present a model that permits good agreement between measured and simulated propagating fields

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

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Scalability upper limit estimation of silicon microring based configurable optical switches

International audienceScalability of a Silicon Micro-Ring switch in a Benes architecture is investigated, modelling waveguide non linearity using experimental data and intra/inter-channel crosstalk. The benefits of double ring configuration is demonstrated both regarding stability and scalability. © 2019 The Author(s

Scalability upper limit estimation of silicon microring based configurable optical switches

International audienceScalability of a Silicon Micro-Ring switch in a Benes architecture is investigated, modelling waveguide non linearity using experimental data and intra/inter-channel crosstalk. The benefits of double ring configuration is demonstrated both regarding stability and scalability. © 2019 The Author(s

Multipolar resonances with designer tunability using VO2 phase-change materials

International audienceSubwavelength nanoparticles can support electromagnetic resonances with distinct features depending on their size, shape, and nature. For example, electric and magnetic Mie resonances occur in dielec-tric particles, while plasmonic resonances appear in metals. Here, we experimentally demonstrate that the multipolar resonances hosted by VO 2 nanocrystals can be dynamically tuned and switched thanks to the insulator-to-metal transition of VO 2. Using both Mie theory and Maxwell-Garnett effective-medium theory, we retrieve the complex refractive index of the effective medium composed of a slab of VO 2 nanospheres embedded in SiO 2 and show that such a resulting metamaterial presents distinct optical tunability compared to unpatterned VO 2. We further show that this approach provides a new degree of freedom to design low-loss phase-change metamaterials with record large figure of merit (n/ k) and designer optical tunability