Development of Photonic Devices Based on the Strained Silicon Technology

[ES] En la última década, la plataforma de silicio ha emergido como la plataforma por excelencia para desarrollar circuitos fotónicos integrados debido a su versatilidad, la posibilidad de miniaturización y de una producción de bajo coste y a gran escala compatible con los sistemas CMOS ("complementary metal-oxide semiconductor"). La conversión de señales eléctricas a alta velocidad en señales ópticas es una función crítica hoy en día tanto para el procesamiento de datos como en el ámbito de las telecomunicaciones. La forma más eficaz de implementar actualementeuna ,modulación electro-óptica ultra-rápida se basa en el efecto Pockels que, de hecho,se encuentra en el corazón de los moduladores comerciales basados en niobato de litio y polímeros. Sin embargo, la implementación de esta funcionalidad se ve impedida en la plataforma de silicio debido a la simetría de inversión de la red cristalina del silicio. En este contexto, el silicio deformado surgió hace más de un decenio como una solución revolucionaria para romper esa centrosimetría y, de ese modo, hacer emerger no-linealidades de segundo orden en el propio silicio. Sin embargo, y a pesar de los alentadores resultados iniciales, estudios posteriores cuestionaron el origen de las respuestas obtenidas, achacando dichos resultados principalmente al efecto de dispersión de plasma. De hecho, más tarde se puso de manifiesto la presencia de varios factores limitantes y, más recientemente, se estimó que el valor del coeficiente χ(2) debía encontrarse en torno a varios pm/V. El trabajo desarrollado en esta tesis tiene como objetivo contribuir a impulsar el campo de silicio deformado mediante la investigación y el abordaje de dichos factores limitantes para, de esta fora, conseguir un efecto Pockels eficiente. Además, las características de captura de carga libre observadas en las estructuras de silicio deformado se han explotado para desarrollar un dispositivo fotónico no volátil.[CA] En l'última dècada, la plataforma de silici ha emergit com la plataforma per excelència per a desenvolupar circuits fotònics integrats a causa de la seua versatilitat i la possibilitat de miniaturització i d'una producció de baix cost i a gran escala compatible amb els sistemes CMOS ("complementary metall-oxide semiconductor"). La conversió de senyals elèctrics a alta velocitat en senyals òptics és una funció crítica hui dia tant per al processament de dades com en l'àmbit de les telecomunicacions. La forma més eficaç d'implementar una modulació electro-òptica ultra-ràpida actualemente es basa en l'efecte *Pockels, que de fet,es troba en el cor dels moduladors comercials basats en el niobato de liti i polímers. No obstant això, la implementació d'aquesta funcionalitat es veu impedida en la plataforma de silici degut a la simetria d'inversió de la xarxa cristal·lina del silici. En aquest context, el silici deformat va sorgir fa més d'un decenni com una solució revolucionària per a trencar aqueixa centrosimetría i, d'aqueixa manera, fer emergir no-linealitats de segon ordre en el propi silici. No obstant això, malgrat els encoratjadors resultats inicials, estudis posteriors van qüestionar l'origen de la resposta obtinguda, atribuint-la principalment a aquest efecte de dispersió de plasma. De fet, més tard es va posar en relleu la presència de diversos factors limitants i, més recentment, es va estimar un valor de χ(2) en el rang de diversos pm/V. El treball desenvolupat en aquesta tesi té com a objectiu contribuir a impulsar el camp de silici deformat mitjançant la investigació i l'abordatge d'aquests factors limitants per a aconseguir un efecte Pockels eficient. A més, les característiques de captura de càrrega lliure observades en les estructures de silici deformat s'han explotat per a desenvolupar un dispositiu fotònic no volàtil.[EN] In the last decade, silicon has emerged as the platform of choice for developing photonic integrated circuits due to its versatility, small footprint and the possibility of a low cost, large-scale CMOS compatible production. The conversion of high-speed electrical signals into optical digital data is a critical function for modern data communication technology. The most effective way for enabling ultra-fast electro-optical modulation is currently based on the Pockels effect, which is the basis of commercial modulators based on lithium niobate and polymers. However, the implementation of such functionality is prevented in the silicon platform due to the inversion symmetry of the silicon lattice. In this context, strained silicon emerged more than a decade ago as a revolutionary solution for breaking that centrosymmetry and, thus, allowing Pockels effect in the silicon material itself. However, despite the encouraging results from initial findings, following studies questioned the origin of the measured electro-optic response. In fact, the presence of several limiting factors was also later highlighted and a rather low strain induced χ(2) in the range of several pm/V was more recently estimated. The work developed on this thesis aims at contributing to push forward the strained silicon field by investigating and tackling such limiting factors to enable an efficient Pockels effect. Furthermore, the trapping properties observed in strained silicon structures have been exploited to develop a non-volatile photonic device.Olivares Sánchez-Mellado, I. (2021). Development of Photonic Devices Based on the Strained Silicon Technology [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/167055TESI

A SiGe Slot Approach for Enhancing Strain Induced Pockels Effect in the Mid-IR Range

[EN] Strained silicon was proposed more than a decade ago promising to revolutionize the silicon photonics field by allowing efficient modulation in this platform. Despite all the efforts, still rather low chi(2) values have been measured in strained silicon devices. In addition, the way of applying strain has not barely changed since the concept was proposed, usually consisting on a silicon waveguide covered by a stressor material such as silicon nitride. In this letter, a SiGe slot approach is explored as a different route to enhance the strain induced Pockels effect in the mid-IR range. Such approach would allow effective index change values which are near to 10(-4) and improve the values expected for the most common silicon - silicon nitride structure by more than three orders of magnitude.This work was supported in part by the Ministerio de Ciencia e Innovacion under Grant TEC2016-76849 and Grant PID2019-111460GB-I00 and in part by the Generalitat Valenciana under Grant PROMETEO/2019/123.Olivares-Sánchez-Mellado, I.; Sanchis Kilders, P. (2021). A SiGe Slot Approach for Enhancing Strain Induced Pockels Effect in the Mid-IR Range. IEEE Photonics Technology Letters. 33(16):848-851. https://doi.org/10.1109/LPT.2021.3075753848851331

Enhanced Pockels effect in strained silicon by means of a SiGe/Si/SiGe slot structure

[EN] A slot waveguide structure made of a SiGe/Si/SiGe heterojunction is proposed to enhance Pockels effect in strained silicon. The strain is applied via lattice mismatch between layers, while the slot configuration optimizes the overlap between the optical and electric field inside the strained silicon.Funding from projects TEC2016-76849 (MINECO/FEDER, UE) and PROMETEO/2019/123 (Generalitat Valenciana) is acknowledged. Irene Olivares acknowledges the UPV for funding her research staff training (FPI) grant.Olivares-Sánchez-Mellado, I.; Sanchis Kilders, P. (2020). Enhanced Pockels effect in strained silicon by means of a SiGe/Si/SiGe slot structure. IEEE. 1-2. https://doi.org/10.1109/IPC47351.2020.9252351S1

Non-Volatile Photonic Memory Based on a SAHAS Configuration

[EN] The non-volatile memory is a crucial functionality for a wide range of applications in photonic integrated circuits, however, it still poses a challenge in silicon photonic technology. This problem has been overcome in the microelectronic industry by using SONOS (silicon-oxide-nitride-oxide-silicon) memory cells, in which the non-volatility is enabled by a dielectric trapping layer such as silicon nitride. Analogously, in this work, a similar approach in which the nitride has been replaced by a hafnium oxide layer, named as SAHAS configuration, is proposed for enabling a programmable erasable photonic memory fully compatible with the silicon platform. The structure features an efficient performance with writing and erasing times of 100 mu s, retention times over 10 years and energy consumption in the pJ range, which improve the current SONOS or floating gate based photonic approaches that exploit the plasma dispersion effect in silicon. The proposed non-volatile photonic memory device shows an extinction ratio above 12 dB and insertion losses below 1 dB in a compact footprint. In addition, because the memory is optically read, ultrafast access times in the picosecond range are also achieved.This work was supported in part by Ministerio de Economia y Competitividad (MINECO/FEDER, UE) (TEC2016-76849), in part by Generalitat Valenciana (PROMETEO/2019/123), in part by Ministerio de Ciencia e Innovacion (MINECO/FEDER, UE) (PID2019-111460GB-I00, FPU17/04224), and in part by Universitat Politecnica de Valencia (FPI Grant).Olivares-Sánchez-Mellado, I.; Parra Gómez, J.; Sanchis Kilders, P. (2021). Non-Volatile Photonic Memory Based on a SAHAS Configuration. IEEE Photonics Journal. 13(2):1-9. https://doi.org/10.1109/JPHOT.2021.3060144S1913

On the influence of interface charging dynamics and stressing conditions in strained silicon devices

[EN] The performance of strained silicon devices based on the deposition of a top silicon nitride layer with high stress have been thoroughly analyzed by means of simulations and experimental results. Results clearly indicate that the electro-optic static response is basically governed by carrier efects. A frst evidence is the appearance of a variable optical absorption with the applied voltage that should not occur in case of having a purely electro-optic Pockels efect. However, hysteresis and saturation efects are also observed. We demonstrate that such efects are mainly due to the carrier trapping dynamics at the interface between the silicon and the silicon nitride and their infuence on the silicon nitride charge. This theory is further confrmed by analyzing identical devices but with the silicon nitride cladding layer optimized to have intrinsic stresses of opposite sign and magnitude. The latter is achieved by a post annealing process which produces a defect healing and consequently a reduction of the silicon nitride charge. Raman measurements are also carried out to confrm the obtained results.Funding from projects TEC2016-76849-C2-2-R (MINECO/FEDER, UE) and NANOMET PLUS-Conselleria d'EducaciA3, Cultura i Esport - PROMETEOII/2014/034 is acknowledged. Irene Olivares also acknowledges the Universitat Politecnica de Valencia for funding his research staff training (FPI) grant. The authors would also like to thank Steven Van Roye from Ghent University for participating in the measurements of the annealed samples.Olivares-Sánchez-Mellado, I.; Ivanova-Angelova, T.; Sanchis Kilders, P. (2017). On the influence of interface charging dynamics and stressing conditions in strained silicon devices. Scientific Reports. 7(7241):1-8. https://doi.org/10.1038/s41598-017-05067-91877241Reed, G. T., Mashanovich, G., Gardes, F. Y. & Thomson, D. J. Silicon optical modulators. Nature Photonics 4, 518–526 (2010).Rao, A. et al. High-performance and linear thin-film lithium niobate Mach-Zehnder modulators on silicon up to 50 GHz. Optics Letters 41, 5700–5703 (2016).Xiong, C. et al. Active silicon integrated nanophotonics: ferroelectric BaT i O 3 devices. Nano Letters 14, 1419–25 (2014).Castera, P., Tulli, D., Gutierrez, A. M. & Sanchis, P. Influence of BaT i O 3 ferroelectric orientation for electro-optic modulation on silicon. Optics Express 23, 15332–15342 (2015).Melikyan, A. et al. High-speed plasmonic phase modulators. Nature Photonics 5–9 (2014).Jacobsen, R. S. et al. Strained silicon as a new electro-optic material. Nature 441, 199–202 (2006).Hon, N. K., Tsia, K. K., Solli, D. R. & Jalali, B. Periodically poled silicon. Applied Physics Letters 94, 091116 (2009).Chmielak, B. et al. Pockels effect based fully integrated, strained silicon electro-optic modulator. Optics Express 19, 17212–17219 (2011).Avrutsky, I. & Soref, R. Phase-matched sum frequency generation in strained silicon waveguides using their second-order nonlinear optical susceptibility. Optics Express 19, 21707–21716 (2011).Schriever, C., Bohley, C., Schilling, J. & Wehrspohn, R. B. Strained Silicon Photonics. Materials 5, 889–908 (2012).Bianco, F. et al. Two-dimensional micro-Raman mapping of stress and strain distributions in strained silicon waveguides. Semiconductor Science and Technology 27, 085009 (2012).Chmielak, B. et al. Investigation of local strain distribution and linear electro-optic effect in strained silicon waveguides. Optics Express 21, 25324–25332 (2013).Aleali, A., Xu, D., Schmid, J. H., Cheben, P. & Winnie, N. Y. Optimization of stress-induced pockels effect in silicon waveguides for optical modulators. In Group IV Photonics (GFP), 2013 IEEE 10th International Conference on, 109–110 (IEEE, 2013).Puckett, M. W., Smalley, J. S., Abashin, M., Grieco, A. & Fainman, Y. Tensor of the second-order nonlinear susceptibility in asymmetrically strained silicon waveguides: analysis and experimental validation. Optics Letters 39, 1693–1696 (2014).Damas, P. et al. Wavelength dependence of pockels effect in strained silicon waveguides. Optics Express 22, 22095–22100 (2014).Khurgin, J. B., Stievater, T. H., Pruessner, M. W. & Rabinovich, W. S. On the origin of the second-order nonlinearity in strained Si-SiN structures. JOSA B 32, 2494–2499 (2015).Manganelli, C. L., Pintus, P. & Bonati, C. Modeling of strain-induced Pockels effect in Silicon. Optics Express 23, 28649–28666 (2015).Damas, P., Marris-Morini, D., Cassan, E. & Vivien, L. Bond orbital description of the strain-induced second-order optical susceptibility in silicon. Physical Review B 93, 165208 (2016).Cazzanelli, M. et al. Second-harmonic generation in silicon waveguides strained by silicon nitride. Nature Materials 11, 148–154 (2012).Schriever, C. et al. Second-Order Optical Nonlinearity in Silicon Waveguides: Inhomogeneous Stress and Interfaces. Advanced Optical Materials 3, 129–136 (2015).Borghi, M. B. et al. High-frequency electro-optic measurement of strained silicon racetrack resonators. Optics Letters 40, 5287–5290 (2015).Azadeh, S. S., Merget, F., Nezhad, M. & Witzens, J. On the measurement of the Pockels effect in strained silicon. Optics Letters 40, 1877–1880 (2015).Sharma, R. et al. Effect of dielectric claddings on the electro-optic behavior of silicon waveguides. Optics Letters 41, 1185–1188 (2016).Borghi, M. et al. Homodyne Detection of Free Carrier Induced Electro-Optic Modulation in Strained Silicon Resonators. Journal of Lightwave Technology 34, 5657–5668 (2016).Olivares, I., Ivanova, T., Pinilla-Cienfuegos, E. & Sanchis, P. A systematic optimization of design parameters in strained silicon waveguides to further enhance the linear electro-optic effect. In SPIE Photonics Europe, 98910E-98910E (International Society for Optics and Photonics, 2016).Warren, W. L., Lenahan, P. & Curry, S. E. First observation of paramagnetic nitrogen dangling-bond centers in silicon nitride. Physical review letters 65, 207 (1990).Warren, W., Kanicki, J., Robertson, J., Poindexter, E. & McWhorter, P. Electron paramagnetic resonance investigation of charge trapping centers in amorphous silicon nitride films. Journal of applied physics 74, 4034–4046 (1993).Bazilchuk, M., Haug, H. & Marstein, E. S. Modulating the fixed charge density in silicon nitride films while monitoring the surface recombination velocity by photoluminescence imaging. Applied Physics Letters 106, 143505 (2015).Stathis, J. H. & Zafar, S. The negative bias temperature instability in MOS devices: A review. Microelectronics Reliability 46, 270–286 (2006).Alam, M. A. & Mahapatra, S. A comprehensive model of PMOS NBTI degradation. Microelectronics Reliability 45, 71–81 (2005).Kufluoglu, H. & Alam, M. A. A computational model of NBTI and hot carrier injection time-exponents for MOSFET reliability. Journal of Computational Electronics 3, 165–169 (2004).Schmidt, J., Schuurmans, F. M., Sinke, W. C., Glunz, S. W. & Aberle, A. G. Observation of multiple defect states at silicon-silicon nitride interfaces fabricated by low-frequency plasma-enhanced chemical vapor deposition. Applied Physics Letters 71, 252–254 (1997).Sanjoh, A., Ikeda, N., Komaki, K. & Shintani, A. Analysis of Interface States between Plasma-CVD Silicon Nitride and Silicon-Substrate Using Deep-Level Transient Spectroscopy. Journal of The Electrochemical Society 137, 2974–2979 (1990).Martnez, F., Mártil, I., González-Daz, G., Selle, B. & Sieber, I. Influence of rapid thermal annealing processes on the properties of SiN x :H films deposited by the electron cyclotron resonance method. Journal of non-crystalline solids 227, 523–527 (1998).Martnez, F. et al. Thermal stability of a-SiN x :H films deposited by plasma electron cyclotron resonance. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 17, 1280–1284 (1999)

Ultra-compact non-volatile Mach-Zehnder switch enabled by a high-mobility transparent conducting oxide

[EN] Compact and broadband non-volatile silicon devices are mainly absorption based. Hence, access to low-loss non-volatile phase shifters is still a challenge. Here, this problem is addressed by using a high-mobility transparent conducting oxide such as cadmium oxide as a floating gate in a flash-like structure. This structure is integrated in a Mach¿Zehnder interferometer switch. Results show an active length of only 30 µm to achieve a ¿¿ phase shift. Furthermore, an extinction ratio of 20 dB and insertion loss as low as 1 dB may be attained. The device shows an optical broadband response and can be controlled with low-power pulses in the nanosecond range. These results open a new, to the best of our knowledge, way for enabling compact silicon-based phase shifters with non-volatile performance.Ministerio de Economia y Competitividad (TEC2016-76849); Generalitat Valenciana (PROMETEO/2019/123); Ministerio de Ciencia, Innovacion y Universidades (FPU17/04224).Parra Gómez, J.; Olivares-Sánchez-Mellado, I.; Ramos, F.; Sanchis Kilders, P. (2020). Ultra-compact non-volatile Mach-Zehnder switch enabled by a high-mobility transparent conducting oxide. Optics Letters. 45(6):1503-1506. https://doi.org/10.1364/OL.388363S1503150645

Gait analysis under the lens of statistical physics

Human gait; Irreversibility; Multi-fractal analysisMarcha humana; Irreversibilidad; Análisis multifractalMarxa humana; Irreversibilitat; Anàlisi multifractalHuman gait is a fundamental activity, essential for the survival of the individual, and an emergent property of the interactions between complex physical and cognitive processes. Gait is altered in many situations, due both to external constraints, as e.g. paced walk, and to physical and neurological pathologies. Its study is therefore important as a way of improving the quality of life of patients, but also as a door to understanding the inner working of the human nervous system. In this review we explore how four statistical physics concepts have been used to characterise normal and pathological gait: entropy, maximum Lyapunov exponent, multi-fractal analysis and irreversibility. Beyond some basic definitions, we present the main results that have been obtained in this field, as well as a discussion of the main limitations researchers have dealt and will have to deal with. We finally conclude with some biomedical considerations and avenues for further development.This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 851255). M.Z. and F.O. acknowledges the Spanish State Research Agency through Grant MDM-2017–0711 funded by MCIN/AEI/10.13039/501100011033. Authors acknowledge support from the Escuela Universitaria de Fisioterapia de la ONCE

Toward Nonvolatile Switching in Silicon Photonic Devices

[EN] Nonvolatile switching is still a missing functionality in current mainstream silicon photonics complementary metal-oxide-semiconductor platforms. Fundamentally, nonvolatile switching stands for the ability to switch between two or more photonic states reversibly without needing additional energy to hold each state. Therefore, such a feature may push one step further the potential of silicon photonics by offering new ways of achieving photonic reconfigurability with ultrasmall energy consumption. Here, a detailed review of current developments that enable nonvolatile switching in silicon photonic waveguide devices is provided. Nonvolatility is successfully demonstrated either based on device engineering or by hybrid integration of silicon waveguides with materials exhibiting unique optical properties. Furthermore, several approaches with high potential for evolving toward a nonvolatile behavior with enhanced performance are also being explored. In most cases, many development steps are still necessary to ensure reliable devices. However, this research field is expected to progress in the coming years boosted by current and emerging applications benefiting from such functionality, such as new paradigms for photonic computing or advanced reconfigurable circuits for programmable photonic systems.This work was supported by Ministerio de Economia y Competitividad (MINECO) (TEC2016-76849); Ministerio de Ciencia e Innovacion (PID2019-111460GB-I00, FPU17/04224); and Generalitat Valenciana (PROMETEO/2019/123).Parra Gómez, J.; Olivares-Sánchez-Mellado, I.; Brimont, ACJ.; Sanchis Kilders, P. (2021). Toward Nonvolatile Switching in Silicon Photonic Devices. Laser & Photonics Review. 15(6):1-18. https://doi.org/10.1002/lpor.20200050111815

Experimental demonstration of a tunable transverse electric pass polarizer based on hybrid VO2/silicon technology

[EN] A tunable transverse electric (TE) pass polarizer is demonstrated based on hybrid vanadium dioxide/silicon (VO2/Si) technology. The 20-mu m-long TE pass polarizer exploits the phase transition of the active VO2 material to control the rejection of the unwanted transverse magnetic (TM) polarization. The device features insertion losses below 1 dB at static conditions and insertion losses of 5.5 dB and an attenuation of TM polarization of 19 dB in the active state for a wavelength range between 1540 nm and 1570 nm. To the best of our knowledge, this is the first time that tunable polarizers compatible with Si photonics are demonstrated. (C) 2018 Optical Society of AmericaMinisterio de Economia y Competitividad (MINECO) (TEC2016-76849); European Commission (EC) [PHRESCO (688579), SITOGA (619456)]; Universitat Politecnica de Valencia; Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT).Sánchez Diana, LD.; Olivares-Sánchez-Mellado, I.; Parra Gómez, J.; Menghini, M.; Homm, P.; Locquet, J.; Sanchis Kilders, P. (2018). Experimental demonstration of a tunable transverse electric pass polarizer based on hybrid VO2/silicon technology. Optics Letters. 43(15):3650-3653. https://doi.org/10.1364/OL.43.003650S365036534315Liu, L., Ding, Y., Yvind, K., & Hvam, J. M. (2011). Efficient and compact TE–TM polarization converter built on silicon-on-insulator platform with a simple fabrication process. Optics Letters, 36(7), 1059. doi:10.1364/ol.36.001059Alonso-Ramos, C., Halir, R., Ortega-Moñux, A., Cheben, P., Vivien, L., Molina-Fernández, Í., … Schmid, J. (2012). Highly tolerant tunable waveguide polarization rotator scheme. Optics Letters, 37(17), 3534. doi:10.1364/ol.37.003534Zhang, H., Das, S., Zhang, J., Huang, Y., Li, C., Chen, S., … Thong, J. T. L. (2012). Efficient and broadband polarization rotator using horizontal slot waveguide for silicon photonics. Applied Physics Letters, 101(2), 021105. doi:10.1063/1.4734640Azzam, S. I. H., Hameed, M. F. O., Areed, N. F. F., Abd-Elrazzak, M. M., El-Mikaty, H. A., & Obayya, S. S. A. (2014). Proposal of an Ultracompact CMOS-Compatible TE-/TM-Pass Polarizer Based on SoI Platform. IEEE Photonics Technology Letters, 26(16), 1633-1636. doi:10.1109/lpt.2014.2329416Dai, D., Wang, Z., Julian, N., & Bowers, J. E. (2010). Compact broadband polarizer based on shallowly-etched silicon-on-insulator ridge optical waveguides. Optics Express, 18(26), 27404. doi:10.1364/oe.18.027404Aamer, M., Gutierrez, A. M., Brimont, A., Vermeulen, D., Roelkens, G., Fedeli, J.-M., … Sanchis, P. (2012). CMOS Compatible Silicon-on-Insulator Polarization Rotator Based on Symmetry Breaking of the Waveguide Cross Section. IEEE Photonics Technology Letters, 24(22), 2031-2034. doi:10.1109/lpt.2012.2218593Xiong, Y., Xu, D.-X., Schmid, J. H., Cheben, P., & Ye, W. N. (2015). High Extinction Ratio and Broadband Silicon TE-Pass Polarizer Using Subwavelength Grating Index Engineering. IEEE Photonics Journal, 7(5), 1-7. doi:10.1109/jphot.2015.2483204Sánchez, L., & Sanchis, P. (2013). Broadband 8 μm long hybrid silicon-plasmonic transverse magnetic–transverse electric converter with losses below 2 dB. Optics Letters, 38(15), 2842. doi:10.1364/ol.38.002842Komatsu, M., Saitoh, K., & Koshiba, M. (2012). Compact Polarization Rotator Based on Surface Plasmon Polariton With Low Insertion Loss. IEEE Photonics Journal, 4(3), 707-714. doi:10.1109/jphot.2012.2195650Caspers, J. N., Alam, M. Z., & Mojahedi, M. (2012). Compact hybrid plasmonic polarization rotator. Optics Letters, 37(22), 4615. doi:10.1364/ol.37.004615Sun, X., Alam, M. Z., Wagner, S. J., Aitchison, J. S., & Mojahedi, M. (2012). Experimental demonstration of a hybrid plasmonic transverse electric pass polarizer for a silicon-on-insulator platform. Optics Letters, 37(23), 4814. doi:10.1364/ol.37.004814Alam, M. Z., Aitchison, J. S., & Mojahedi, M. (2011). Compact and silicon-on-insulator-compatible hybrid plasmonic TE-pass polarizer. Optics Letters, 37(1), 55. doi:10.1364/ol.37.000055Jin, L., Chen, Q., & Wen, L. (2014). Mode-coupling polarization rotator based on plasmonic waveguide. Optics Letters, 39(9), 2798. doi:10.1364/ol.39.002798Caspers, J. N., Aitchison, J. S., & Mojahedi, M. (2013). Experimental demonstration of an integrated hybrid plasmonic polarization rotator. Optics Letters, 38(20), 4054. doi:10.1364/ol.38.004054Briggs, R. M., Pryce, I. M., & Atwater, H. A. (2010). 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Qué significa “jugar bien” para los entrenadores de élite: El pensamiento implícito de los entrenadores de fútbol españoles

People construct knowledge through a set of highly diverse experiences. Despite being personal, this knowledge is strongly influenced by the specific context where it occurs. Such experience-based knowledge is referred to as ‘implicit theories’ because it does not fit in with a systematic and theoretical knowledge context like that of scientific knowledge. Coaches work with a number of implicit theories about aspects such as players, competition or training which determine their professional behaviour to a considerable extent. Thirty-nine Spanish First Division coaches were asked the question ‘What does playing soccer well mean?’ in this study. Their responses were later classified into eight different categories which show the diversity of opinions regarding this matter as well as the possible implicit theories that would guide coaches’ actions.Las personas construyen el conocimiento a través de una serie de experiencias diversas. Este conocimiento, aunque de carácter personal, está muy influenciado por el contexto en que se desarrolla, por lo que parte del mismo se basa en experiencias que son denominadas “teorías implícitas”, porque no se corresponden con un conocimiento sistemático y teórico como es el conocimiento científico. Los entrenadores trabajan con un número de teorías implícitas acerca de los jugadores, la competición, el entrenamiento, etc., que determinan en gran medida su comportamiento profesional. En este estudio hemos preguntado a treinta y nueve entrenadores de la Primera División de la Liga Española de Fútbol la siguiente pregunta: ‘¿Qué significa jugar bien al fútbol?’ Sus respuestas han sido clasificadas en ocho categorías diferentes, que muestran la diversidad de opiniones sobre esta cuestión y las posibles teorías implícitas que guían sus acciones