Integrated photonic tunable basic units using dual-drive directional couplers

"© 2019 Optical Society of America. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited"[EN] Photonic integrated circuits based on waveguide meshes and multibeam interferometers call for large-scale integration of Tunable Basic Units (TBUs) that feature beam splitters and waveguides. This units are loaded with phase actuators to provide complex linear processing functionalities based on optical interference and can be reconfigured dynamically. Here, we propose and experimentally demonstrate, to the best of our knowledge, for the first time, a thermally actuated Dual-Drive Directional Coupler (DD-DC) design integrated on a silicon nitride platform. It operates both as a standalone optical component providing arbitrary optical beam splitting and common phase as well as a low loss and potentially low footprint TBU. Finally, we report the experimental demonstration of the first integrated triangular waveguide mesh arrangement using DD-DC based TBUs and provide an extended analysis of its performance and scalability. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing AgreementEuropean Research Council (ERC ADG-2016UMWP-Chip, ERC-POC-2019 FPPAs); Generalitat Valenciana (PROMETEO 2017/017); European Cooperation in Science and Technology (COST Action CA16220 EUIMWP.).Pérez-López, D.; Gutierrez Campo, AM.; Sánchez-Gomáriz, E.; Dasmahapatra, P.; Capmany Francoy, J. (2019). Integrated photonic tunable basic units using dual-drive directional couplers. Optics Express. 27(26):38071-38086. https://doi.org/10.1364/OE.27.03807138071380862726Soref, R. (2006). The Past, Present, and Future of Silicon Photonics. IEEE Journal of Selected Topics in Quantum Electronics, 12(6), 1678-1687. doi:10.1109/jstqe.2006.883151Somekh, S., Garmire, E., Yariv, A., Garvin, H. L., & Hunsperger, R. G. (1974). Channel Optical Waveguides and Directional Couplers in GaAs–Imbedded and Ridged. Applied Optics, 13(2), 327. doi:10.1364/ao.13.000327Pérez, D., Gasulla, I., Capmany, J., & Soref, R. A. (2016). Reconfigurable lattice mesh designs for programmable photonic processors. Optics Express, 24(11), 12093. doi:10.1364/oe.24.012093Clements, W. R., Humphreys, P. C., Metcalf, B. J., Kolthammer, W. S., & Walsmley, I. A. (2016). Optimal design for universal multiport interferometers. Optica, 3(12), 1460. doi:10.1364/optica.3.001460Zhuang, L., Roeloffzen, C. G. H., Hoekman, M., Boller, K.-J., & Lowery, A. J. (2015). Programmable photonic signal processor chip for radiofrequency applications. Optica, 2(10), 854. doi:10.1364/optica.2.000854Pérez, D., Gasulla, I., Crudgington, L., Thomson, D. J., Khokhar, A. Z., Li, K., … Capmany, J. (2017). Multipurpose silicon photonics signal processor core. Nature Communications, 8(1). doi:10.1038/s41467-017-00714-1Perez-Lopez, D., Sanchez, E., & Capmany, J. (2018). Programmable True Time Delay Lines Using Integrated Waveguide Meshes. Journal of Lightwave Technology, 36(19), 4591-4601. doi:10.1109/jlt.2018.2831008Kogelnik, H., & Schmidt, R. (1976). Switched directional couplers with alternating ΔΒ. IEEE Journal of Quantum Electronics, 12(7), 396-401. doi:10.1109/jqe.1976.1069190Schmidt, R. V., & Kogelnik, H. (1976). Electro‐optically switched coupler with stepped Δβ reversal using Ti‐diffused LiNbO3waveguides. Applied Physics Letters, 28(9), 503-506. doi:10.1063/1.88833Alferness, R. C., & Veselka, J. J. (1985). Simultaneous modulation and wavelength multiplexing with a tunable Ti:LiNbO3directional coupler filter. Electronics Letters, 21(11), 466-467. doi:10.1049/el:19850330Sharkawy, A., Shi, S., Prather, D. W., & Soref, R. A. (2002). Electro-optical switching using coupled photonic crystal waveguides. Optics Express, 10(20), 1048. doi:10.1364/oe.10.001048Orlandi, P., Morichetti, F., Strain, M. J., Sorel, M., Melloni, A., & Bassi, P. (2013). Tunable silicon photonics directional coupler driven by a transverse temperature gradient. Optics Letters, 38(6), 863. doi:10.1364/ol.38.000863Pérez, D., & Capmany, J. (2019). Scalable analysis for arbitrary photonic integrated waveguide meshes. Optica, 6(1), 19. doi:10.1364/optica.6.000019Rios, C., Stegmaier, M., Cheng, Z., Youngblood, N., Wright, C. D., Pernice, W. H. P., & Bhaskaran, H. (2018). Controlled switching of phase-change materials by evanescent-field coupling in integrated photonics [Invited]. Optical Materials Express, 8(9), 2455. doi:10.1364/ome.8.002455Zheng, J., Khanolkar, A., Xu, P., Colburn, S., Deshmukh, S., Myers, J., … Majumdar, A. (2018). GST-on-silicon hybrid nanophotonic integrated circuits: a non-volatile quasi-continuously reprogrammable platform. Optical Materials Express, 8(6), 1551. doi:10.1364/ome.8.001551Capmany, J., Domenech, D., & Muñoz, P. (2014). Silicon graphene waveguide tunable broadband microwave photonics phase shifter. Optics Express, 22(7), 8094. doi:10.1364/oe.22.008094Abel, S., Eltes, F., Ortmann, J. E., Messner, A., Castera, P., Wagner, T., … Fompeyrine, J. (2018). Large Pockels effect in micro- and nanostructured barium titanate integrated on silicon. Nature Materials, 18(1), 42-47. doi:10.1038/s41563-018-0208-0Sanchez, L., Lechago, S., Gutierrez, A., & Sanchis, P. (2016). Analysis and Design Optimization of a Hybrid VO2/Silicon2 $\times$ 2 Microring Switch. IEEE Photonics Journal, 8(2), 1-9. doi:10.1109/jphot.2016.2551463Qiao, L., Tang, W., & Chu, T. (2017). 32 × 32 silicon electro-optic switch with built-in monitors and balanced-status units. Scientific Reports, 7(1). doi:10.1038/srep42306Zheng, D., Doménech, J. D., Pan, W., Zou, X., Yan, L., & Pérez, D. (2019). Low-loss broadband 5  ×  5 non-blocking Si3N4 optical switch matrix. Optics Letters, 44(11), 2629. doi:10.1364/ol.44.002629Capmany, J., Gasulla, I., & Pérez, D. (2015). The programmable processor. Nature Photonics, 10(1), 6-8. doi:10.1038/nphoton.2015.254Carolan, J., Harrold, C., Sparrow, C., Martín-López, E., Russell, N. J., Silverstone, J. W., … Laing, A. (2015). Universal linear optics. Science, 349(6249), 711-716. doi:10.1126/science.aab3642Lee, B. G., & Dupuis, N. (2019). Silicon Photonic Switch Fabrics: Technology and Architecture. Journal of Lightwave Technology, 37(1), 6-20. doi:10.1109/jlt.2018.2876828Seok, T. J., Quack, N., Han, S., Muller, R. S., & Wu, M. C. (2016). Large-scale broadband digital silicon photonic switches with vertical adiabatic couplers. Optica, 3(1), 64. doi:10.1364/optica.3.00006

Impact of the external resistance on the switching power consumption in VO2 nano gap junctions

[EN] The influence of an external resistance on the performance of VO2 nanogap junctions is analyzed and experimentally characterized. The current-voltage response shows the reversible metal-insulator transition typical of VO2 based devices. When reaching the metallic state, the current through the VO2 junction is abruptly increased, which may result in electrical contact damage. Therefore, an external resistance in series with the VO2 junction is usually employed to limit the maximum current through the device. Our results indicate that the external resistance plays a key role in the switching power consumption showing an optimum value, which depends on the dimensions of the VO2 junction. In such a way, power consumption reductions up to 90% have been demonstrated by selecting the optimum external resistance value.This work was supported by the European Commission under Project No. FP7-ICT-2013-11-619456 SITOGA. Financial support from TEC2016-76849-C2-2-R and NANOMET Conselleria de Educacio, Cultura i Esport-PROMETEOII/2014 034 is also acknowledged. P.H. acknowledges support from Becas Chile-CONICYT.Sánchez Diana, LD.; Rosa Escutia, Á.; Griol Barres, A.; Gutierrez Campo, AM.; Homm, P.; Van Bilzen, B.; Menghini, M.... (2017). Impact of the external resistance on the switching power consumption in VO2 nano gap junctions. Applied Physics Letters. 111(3):1-4. https://doi.org/10.1063/1.4994326S14111

Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome : Insights from the LUNG SAFE study

Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study. Methods: In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO2 > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO2 ≥ 0.60 during hyperoxemia). Results: Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO2 < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO2 use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO2 use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO2. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO2 use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO2 use, compared to 39% in a propensity-matched sample of normoxemic (PaO2 55-100 mmHg) patients (P = 0.47). Conclusions: Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort. Trial registration: LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073publishersversionPeer reviewe

Dementia in Latin America : paving the way towards a regional action plan

Regional challenges faced by Latin American and Caribbean countries (LACs) to fight dementia, such as heterogeneity, diversity, political instabilities, and socioeconomic disparities, can be addressed more effectively grounded in a collaborative setting based on the open exchange of knowledge. In this work, the Latin American and Caribbean Consortium on Dementia (LAC-CD) proposes an agenda for integration to deliver a Knowledge to Action Framework (KtAF). First, we summarize evidence-based strategies (epidemiology, genetics, biomarkers, clinical trials, nonpharmacological interventions, networking and translational research) and align them to current global strategies to translate regional knowledge into actions with transformative power. Then, by characterizing genetic isolates, admixture in populations, environmental factors, and barriers to effective interventions and mapping these to the above challenges, we provide the basic mosaics of knowledge that will pave the way towards a KtAF. We describe strategies supporting the knowledge creation stage that underpins the translational impact of KtAF

Design method for high performance grating couplers in photonic integrated circuits

[EN] The optimization of grating couplers is usually realized by multiple simulations using specific computational software for this task. Many grating parameters must be analyzed and designed to get the maximum coupling efficiency and the transmission spectrum centred at the wavelength of operation. However, these simulations may take a long time and consume high computational resources depending on the simulation resolution. This work is focused on finding a method to optimize the grating parameters with the lowest number of simulations. In this way, closed-form expressions are presented to get the optimal values for the period and fill-factor, which are the main parameters in the grating design. The usefulness of the proposed approach is shown for the design of silicon grating couplers operating at 1.31 ¿m and 1.55 ¿m and both TE and TM polarizations.Funding from Project TEC2016-76849 (MINECO/FEDER, UE) is acknowledged. Roberto Larrea also acknowledges the Ecuadorian Government for Funding his Grant.Larrea-Luzuriaga, RA.; Gutierrez Campo, AM.; Sanchis Kilders, P. (2018). Design method for high performance grating couplers in photonic integrated circuits. Optical and Quantum Electronics. 50(9):1-9. https://doi.org/10.1007/s11082-018-1596-8S1950

Dual-Drive Directional Couplers for Programmable Integrated Photonics

[EN] We propose and experimentally demonstrate the use of directional couplers with an independent phase actuator on each waveguide. We show the configurations that allow the setting of the splitting ratio and the phase in a silicon-nitride platform and their applications in programable photonic integrated circuits.Pérez-López, D.; Gutierrez Campo, AM.; Sánchez-Gomáriz, E.; Dasmahapatra, P.; Capmany Francoy, J. (2019). Dual-Drive Directional Couplers for Programmable Integrated Photonics. IEEE. 1-2. https://doi.org/10.1109/PHOSST.2019.8794902S1

Resonant nanopillars as label-free optical biosensors

In recent works, it has been demonstrated the suitability of using resonant nanopillars (R-NPs) as biochemical. In this work, it has been shown the capability of the R-NPs to behave as label-free multiplexed biological sensors. Each R-NP is formed by silicon oxide (SiO2) and silicon nitride (Si3N4) Bragg reflectors and a central cavity of SiO2, and they are grouped into eight arrays called BICELLs, which are distributed on a single chip of quartz substrate for multiplexing measurements. For the biological sensing assessment, it was developed an immunoassay on the eight single BICELLs. The biofunctionalization process was performed by a silanization protocol based on 3-aminopropyltrymethoxysilane (APTMS) and glutaradheyde (GA) as a linker between APTMS and the IgG which acted as bioreceptor for the anti-IgG recognition. In this work, there were compared two forms of immobilization: on one hand by incubating the R-NPs under static drop of 50 ?g/mL and on the second hand by introducing the sensing chip in a flow cell with a continuous flow of the same concentration of IgG. The eight arrays of R-NPs or BICELLs were independently optically interrogated by a bundle of fiber connected to a spectrometer. The multiplexing analysis showed reproducibility among the BICELLs, suggesting the potentially of using R-NPs for multiplexed biosensors. Performance in the immobilization process apparently does not have a signification effect. However, the election of one method or another should be a commitment between time and resources

Development towards Compact Nitrocellulose-Based Interferometric Biochips for Dry Eye MMP9 Label-Free In-Situ Diagnosis

A novel compact optical biochip based on a thin layer-sensing surface of nitrocellulose is used for in-situ label-free detection of metalloproteinase (MMP9) related to dry eye disease. In this article, a new integrated chip with different interferometric transducers layout with an optimal sensing surface is reported for the first time. We demonstrate that specific antibodies can be immobilized onto these transducers with a very low volume of sample and with good orientation. Many sensing transducers constitute the presented biochip in order to yield statistical data and stability in the acquired measurements. As a result, we report the recognition curve for pure recombinant MMP9, tests of model tears with MMP9, and real tear performance from patients, with a promising limit of detection

Biochemical assay development for optimization of immunological system inhibitors

The aim of this work was to adapt BioD Point of Care technology in order to evaluate immunologic system inhibitors through a chemical assay that is able to identify the inhibition ability of new drugs for the treatment of autoimmune disease