terceras jornadas jÓvenes icmuv 2015/imagenes noticias... · terceras jornadas jÓvenes icmuv 1...
TRANSCRIPT
Scientists just wanna have fun
TERCERAS JORNADAS JÓVENES ICMUV Viernes, 22 de junio, 12h
TERCERAS JORNADAS JÓVENES ICMUV
1
- First data on the characterization of siliceous raw materials and the catchment areas from Cova de les Malladetes (Barx, Valencia)
Aleix Eixea, Álvaro Martínez-Alfaro, Miguel Ángel Bel, Clodoaldo Roldán, Sonia Murcia, David Vie, M.
Isabel Dias, M. Isabel Prudêncio, Rosa Marques, Alfred Sanchis, Valentín Villaverde
2
- Analysis of polarization modulation instability in all-normal dispersion photonic crystal fibers A. Loredo-Trejo*, Y. Lopez-Dieguez, A. Díez y M. V. Andrés
3
- Novel transparent conducting polymeric materials suitable for hole transport in perovskite-based devices Pedro Rodríguez-Cantó, Eduardo Aznar, Juan P. Martínez-Pastor, Rafael Abargues
4 - Fiber Bragg gratings in tapered multimode fibers
Luis A. Herrera-Piad, Martina Delgado, José L. Cruz, Miguel V. Andrés
5
- Experimental observation of polarization modulation instability in an all-normal dispersion photonic crystal fiber. Y. Lopez-Dieguez, L. Velázquez-Ibarra, A. Loredo-Trejo, A. Díez, M. V. Andrés
6
- Cladding refractive index perturbation in single mode fibers: matching the experimental dispersion curves
Aktham Tashtush, Enrique Silvestre, Antonio Díez, and Miguel V. Andrés
7
- Desarrollo de materiales híbridos para aplicaciones termoeléctricas José F. Serrano-Claumarchirant, Alvaro Seijas, Anabel López
8
- ESA/VSC Laboratorio Europeo de Materiales de Alta Potencia para el Espacio. Consorcio Espacial Valenciano
Rafael Mata Sanz, Benito Gimeno Martínez
9 - Epitaxial graphene as Van der Waals substrate for GaN growth: structural and
electrical characterization O. Klymov, Z. Seoudi, N. Garro, A. Cros*, M. Gruart, N. Feldberg and B. Daudin
10
- Ring versus Fabry-Pérot Passive Mode-Locked Fiber Laser Set-Up Antonio Carrascosa*, José L. Cruz, Antonio Díez and Miguel V. Andrés
11
- Crystalline-size Dependence of Dual Emission Peak on Hybrid Organic Lead Iodide Perovskites Films at Low Temperature
Raquel Chulia-Jordan *, Elena Mas-Marzá, Juan Martínez-Pastor
12
- Structural and vibrational properties of GdVO4 under high pressure T. Marqueño,*, D. Errandonea, D. Santamaría-Pérez, D. Martínez-García, J. Pellicer-Porres, P. Rodríguez-Hernández, S. Radescu, A. Muñoz, C. Popescu, S. N. Achary, A. K. Tyagi
13 - Coupled surface acoustic waves cavities
A. L. O. Bilobran, M. M. de Lima and P. V. Santos
14 - Measurement of UV-induced losses in photosensitive fibers X. Roselló-Mechó, M. Delgado-Pinar, J.L. Cruz, A. Diez and M.V. Andrés
15
- Effects in long period gratings due to high power pulse propagation. E. Rivera-Pérez, Antonio Díez, Antonio Carrascosa, Miguel V. Andrés.
16 - Interacción acusto-óptica en fibra óptica de dos modos
Saúl Rosales-Mendoza*, Martina Delgado-Pinar, A. Díez, Miguel V. Andrés Bou
17 - Combination of the atrane and Stöber method for the obtaining of Mesoporous
Materials Based on Silica and doped with different Metals Carolina García-Llacer, Rahma Hany, Jamal el Haskouri, Aurelio Beltrán and Pedro Amorós
18 - Acoustically tuned dynamic wavelength division multiplexing devices
Dominik D. Bühler*, A. Crespo-Poveda, A. Cantarero and M. M. de Lima Jr. 19
- Versatility and Sustainability in the Development of Polyurethane Formulations Manuel Asensio, Juan F. Ferrer-Crespo, Ana C. Puig, Diana Favero, Rafael Muñoz-Espí, ClaraM.Gómez
20
- Multifunctional Hybrid Colloids: Polymers and Inorganics Meet at the Nanoscale Adrián Aguado-Hernándiz, Amparo Sánchez-Soler, Ana Torres-Suay, Hilario Verdeguer-Asensio, Olaia Álvarez-
Bermúdez, Clara M. Gómez, Francisco F. Pérez-Pla, Katharina Landfester, Rafael Muñoz-Espí,*
First data on the characterization of siliceous raw materials and the
catchment areas from Cova de les Malladetes (Barx, Valencia)
Aleix Eixea1,2,3
, Álvaro Martínez-Alfaro4,3
, Miguel Ángel Bel4,3
, Clodoaldo Roldán5,
Sonia Murcia5, David Vie
5, M. Isabel Dias
6, M. Isabel Prudêncio
6, Rosa Marques
6,
Alfred Sanchis7, Valentín Villaverde
4,3
(1) Institut Català de Paleoecologia Humana i Evolució Social (IPHES), Zona Educacional 4,
Campus Sescelades URV (Edifici W3), 43007 Tarragona, Spain.
(2) Àrea de Prehistòria, Universitat Rovira i Virgili (URV), Avinguda de Catalunya 35,
43002 Tarragona, Spain.
(3) PREMEDOC Research Group (GIUV2015-213).
(4) Departament de Prehistòria, Arqueologia i Història Antiga, Universitat de València, Av.
Blasco Ibañez 28, 46010 Valencia, Spain.
(5) Instituto de Ciencia de los Materiales, Universidad de Valencia (ICMUV), C/
Catedrático José Beltrán 2, 46980 Paterna, Valencia, Spain. (
6) Centro de Ciências e Tecnologias Nucleares (C
2TN), Instituto Superior Técnico,
Universidade de Lisboa, E.N. 10, km 139.7, 2695-066 Bobadela, Portugal.
(7) Museu de Prehistòria de València, Servei d’Investigació Prehistòrica, Diputació de
València, Corona 36, 46003 València, Spain.
Abstract
The purpose of this communication is to present the preliminary results of raw
materials and catchment areas from the new excavations carried out in Cova de les
Malladetes. The cavity has a wide stratigraphic sequence that goes from the
Aurignacian (without having reached the base) to the Neolithic period but our interest is
focused on the part belonging to the Upper Palaeolithic. In relation to the raw materials
used, the studies have not gone beyond simple and vague descriptions so it was
necessary to study the new materials obtained and a review of the previous campaigns
of the 50s and 70s. Currently, except for some case studies, investigations about
siliceous resources exploited during prehistoric times in the Valencian region are still
scarce and, generally, they did not employ methods which go deeply into the
provenance characteristics.
Within a new program of prospections that we are carrying out in the central
area of the Mediterranean Iberia, we include data from this site as well as others
belonging to Upper and Middle Palaeolithic such as Cova Matutano, Cova Fosca, El
Pinar, Abrigo de la Quebrada, Las Fuentes, Cova Negra, Petxina, Cova del Parpalló,
Cova de les Calaveres, Cova de les Cendres or Ratlla del Bubo which also serve as a
comparative framework. All of them are related to the outcrops found. To this first step
of prospecting and macroscopic samples description, we add the analysis of both
petrographic (petrographic microscopy and XRD) and geochemical analyses (ED-XRF
and INAA).
The results show an outstanding component of local and semi-local catchment,
but without forgetting the interesting presence of allochthones types that demonstrates
long lithic raw material circulation and a high human mobility in the central region of
Mediterranean Iberia during the Upper Palaeolithic.
dΛ
Analysis of polarization modulation instability in all-normal dispersion photonic crystal fibers
A. Loredo-Trejo*, Y. Lopez-Dieguez, A. Díez y M. V. Andrés
Departamento de Física Aplicada y Electromagnetismo, Universidad de Valencia, c/ Dr. Moliner 50, 46100, Burjassot, Valencia, España.
*e-mail: [email protected]
Abstract: A theoretical study of the polarization modulation instability effect in all-normal dispersion photonic crystal fibers with small birefringence is reported. A vectorial approach is used to describe the nonlinear interaction. Stokes and anti-Stokes parametric wavelengths are predicted as a function of the pump wavelength.
In the last years, all-normal dispersion (ANDi) photonic crystal fibers (PCFs) have arisen great attention for
nonlinear applications due to the particular dispersion properties of such fibers. In applications such as supercontinuum generation [1] (SC) or pulse compression [2], the dispersion profile that exhibits these kind of fibers, i.e. a convex profile lying completely in the normal dispersion region, leads to quite different nonlinear response than PCFs with a more conventional dispersion profile with anomalous dispersion regions. Pumping by femtosecond few-nJ pulses near the flattened top of the dispersion curve generates highly coherent, flat-top, octave-spanning SCs, thereby preserving a single pulse in the temporal domain [3] and allowing efficient pulse temporal compression with a simple compressor. The physical mechanism of SC generation in ANDi PCFs differs from the corresponding mechanism in fibers with anomalous dispersion region. In ANDi PCFs that are pumped with short pulses, spectral broadening is generated essentially as a result of self-phase modulation (SPM).
In general, all optical fibers exhibits an intrinsic small birefringence due to the residual stress and/or the non-perfect circular symmetry. ANDi PCFs are not an exception and residual birefringence values in the order of 10-5 are present in these type of fibers. Although such birefringence is very small, from the theoretical point of view it opens the possibility that an additional nonlinear effect (apart from SPM) known as polarization modulation instability (PMI) can be generated when the fiber is pumped.
PMI leads to the generation of two sidebands around the pump, the polarization of which is orthogonal to the polarization of the pump. We investigate this effect using a vectorial analysis [4] to describe the nonlinear interaction. Some preliminary results are shown in Fig. 1. We want to notice that in these type of fibers, PMI is produced only when the polarization of the pump is oriented to the slow axis (S) and, consequently, the parametric bands are generated in the fast mode (F).
750 1000 1250 1500 1750 2000-200
-150
-100
-50
0
50
Λ=1.1µm
Λ=1.2 µm
Disp
ersio
n (p
s/km
-nm
)
Wavelength (nm)
PCF A PCF B PCF C
(a)
Λ=1.33µm
d/Λ = 0.48
Stokes anti-Stokes
750 900 1050 1200750875
100011251250
750 900 1050 1200750875
100011251250
750 900 1050 1200750875
100011251250
PCF A
PMI (
nm)
Pump (nm)
(b)
PCF B
PMI (
nm)
Pump (nm)
PCF C
PMI (
nm)
Pump (nm) Figure 1. (a) Chromatic dispersion as a function of wavelength for some ANDi PCFs. The structural parameters of
the fibers are indicated in the figure. (b) Stokes and anti-Stokes PMI wavelengths as a function of the pump wavelength for the process S-F.
References [1] J. M. Dudley, J. R. Taylor, Supercontinuum generation in optical fibers, (Cambridge University Press), (2010). [2] B. Nikolaus and D. Grischkowsky, “12× pulse compression using optical fibers”, Appl. Phys. Lett., 42, (1) (1983). [3] I. A. Sukhoivanov, S. O. Iakushev, O. V. Shulika, J. A. Andrade-Lucio, A. Díez, and M. Andrés, "Supercontinuum
generation at 800 nm in all-normal dispersion photonic crystal fiber," Opt. Express 22, (30234), (2014). [4] G. Agrawal, Nonlinear Fiber Optics, (Academic Press), (2013).
Novel transparent conducting polymeric materials suitable for hole
transport in perovskite-based devices
Pedro Rodríguez-Cantó 1 Eduardo Aznar 2, Juan P. Martínez-Pastor 2, Rafael Abargues 2 1 INTENANOMAT S.L, C/ Catedrático José Beltrán 2, 46980 Paterna, Spain. 2 Instituto de Ciencia de los Materiales, Universidad de Valencia, P.O. Box 22085, 46071
Valencia, Spain
*E-mail: [email protected]
The incorporation of hole transport materials (HTMs) in perovskite solar cells (PSCs) is
crucial to improve the device performance and the operational stability. These materials
play a key role because they selectively improve hole transport efficiency, blocks the
electron transfer to anode, and avoid degradation at a metal-perovskite interface [1].
A broad number of HTMs (inorganic materials, small molecules and polymers) has been
reported and tested in diverse PSC architectures, resulting in different power conversion
efficiencies and stabilities [2].
Commercially available PEDOT:PSS is the most commonly HTM used in inverted PSCs
as well as in organic photovoltaics. However, this material is very sensitive to humidity,
has poor film-forming properties and causes corrosion at the adjacent layers in the device
due to the strong acidic nature of polystyrenesulfonate (PSS). Additionally, PEDOT:PSS
cannot be optimally integrated in conventional PSC structures (n-i-p) because water
strongly degrades perovskite layers. Other alternatives, such as inorganic HTMs possess
high hole-mobility and stability, but present some drawbacks in terms of solvent
compatibility with the perovskite. Moreover, polymer-based HTMs or small molecules
such as spiro-type HTMs have led to remarkable power conversion efficiencies but
considerations on costs, processing and stability make researchers to consider other
materials [1].
Consequently, there is a need to explore alternative HTMs that combine high photovoltaic
performance with low production costs. Furthermore, it is quite challenging the
development of HTMs suitable to be incorporated on top of the perovskite layer in
conventional PSCs [3].
Here, we present a new generation of transparent conducting materials with suitable
characteristics for efficient charge transport in photovoltaic and electroluminescent
applications. These materials are synthesized by the in situ oxidative polymerization of
EDOT-based monomers and derivatives inside a transparent host polymer. As a result,
homogeneous ultrathin films (up to 10 nm) with high transparency (greater than
PEDOT:PSS, especially in the NIR) and tunable conductivities from 10-4 to 600 S/cm
can be synthesized to successfully fulfill all the specific requirements of any PSC
architecture. Besides, our material can be properly formulated with a wide range of
solvents to be absolutely compatible with perovskite-based devices. In this work, we will
also discuss the optical and optoelectronic characterization and will demonstrate the
efficient use of this material as HTM in some perovskite-based devices.
[1] L. Calió, et al., Angew. Chem. Int. Ed. 2016, 55, 14522
[2] Z.H. Bakr, et al., NanoEnergy, 2017, 34, 271-305
[3] Xiaoqing Jiang et al., Scientific Reports, 2017, 7, 42564
Fiber Bragg gratings in tapered multimode fibers
Luis A. Herrera-Piad1 2, Martina Delgado1, José L. Cruz1, Miguel V. Andrés1 1Departamento de Física Aplicada, ICMUV, Universidad de Valencia, Dr. Moliner 50, 46100
Burjassot, Spain. 2Departamento de Electrónica, División de Ingenierías Campus Irapuato-Salamanca,
Universidad de Guanajuato, Carretera Salamanca-Valle de Santiago km 3.5 + 1.8 km,
Salamanca, Gto. 36885, Mexico.
*E-mail: [email protected]
During more than 50 years researchers have been trying to find novelty ways to make fiber
lasers. The use of doping with rare earth elements for pulsed lasers have been recently
exposed, and continuous wave lasers still working with fiber optic structures to increase the
number of laser lines. Some of these structures are fiber gratings [1], special fibers as
photonic crystal, twin-core and polarization maintaining fibers, and tapered optical fibers [2].
The primary goal of this research is to transform a multimode fiber to single-mode trough
taper fabrication. In this work we propose to use a tapered multimode optical fiber fabricated
by flame technique to make necessary the fiber only supports the fundamental mode, in order
to be used for lasers by recording fiber Bragg gratings.
In this case we present the experimental results for a fiber that supports four propagation
modes. This fiber was stretched until 50 microns of waist diameter, and as is seen in figure 1
the Bragg grating spectrum only shows the fundamental mode in transmission. In reflection
we prove that the other modes that appears belong to the cladding by adding oil with a higher
refractive index to remove them. It is important to emphasize that this result can be
implemented in lasers using the bigger modal area of the multimode fiber as advantage, also
for sensing applications using the cladding modes to measure any change in the spectrum
when perturbations are applied.
Figure 1.-Fiber Bragg
grating spectrum.
[1] Liu X, Yang X, Lu F, Ng J, Zhou X and Lu C “Stable and uniform dual-wavelength
erbium-doped fiber laser based on fiber Bragg gratings and photonic crystal fiber” Opt.
Express 13 142 (2004).
[2] Alvarez-Chavez J A, Grudinin A B, Nilsson J, Turner P W and Clarkson W A “Mode
selection in high power cladding pumped fibre lasers with tapered” Proc. CLEO IEEE,
Baltimore (1999).
Experimental observation of polarization modulation instability in an
all-normal dispersion photonic crystal fiber.
Y. Lopez-Dieguez1, L. Velázquez-Ibarra
1, A. Loredo-Trejo
1, A. Díez
1, M. V. Andrés
1
1) Departamento de Física Aplicada y Electromagnetismo, Universitat de Valencia, Edificio de
investigación c/ Dr. Moliner 50, 46100, Burjassot, Valencia, España.
*E-mail: [email protected]
Polarization Modulation Instability (PMI) is a form of modulation instability that can occur in
birefringent optical fibers. PMI occurs when an intense pump signal is launched on one axes
of the fiber and two waves (Stokes and Anti-Stokes sidebands) that are polarized orthogonally
to the pump are generated [1]. Here, we report the experimental observation of PMI in an
all-normal dispersion (ANDi) photonic crystal fiber (PCFs) with small residual birefringence.
The ANDi PCF used in this experiment was fabricated at the Universidad de Valencia
following the stack-and-draw technique. The microstructure parameters are the pitch ( =1
m) and the air hole diameter (d = 0.53 m). The chromatic dispersion of this fiber at 1064
nm is around -100 ps/nm km and the residual birefringence is about 1.2×10-5
.
In the experimental setup we use a microchip Nd:YAG laser as pump source. The output
spectrum was analyzed for different pump power values and polarization orientations. In
addition to Stokes and anti-Stokes Raman scattering, two narrow bands at 1026 nm and 1105
nm are shown (Figure 1). We confirmed that the polarization of these two bands is orthogonal
to the pump polarization and their intensity depends of the polarization orientation of the
pump (Figure 2).
1015 1044 1073 1102 1131
-76
-57
-38
-19
RAMAN
Inte
nsity (
dB
m)
Wavelength (nm)
ANTI-STOKES
~1026 nm
STOKES
~1105.5 nm
RAMAN
PUMP
1064 nm
PMI bands
Figure 1: Experimental output
spectrum with PMI Stokes
and Anti-Stokes bands.
1012.0 1017.5 1023.0 1028.5
-77
-66
-55
-44
Inte
nsity (
dB
m)
Wavelength (nm)
0°
45°
Polarization Dependence
Figure 2: Spectrum with
pump polarization orientation
adjusted to obtain maximum
(black) and minimum (red)
PMI generation efficiency.
[1] Nonlinear Fiber Optics, G. Agrawal, Academic Press, 2013.
Cladding refractive index perturbation in single mode fibers: matching the
experimental dispersion curves
Aktham Tashtush(1)
, Enrique Silvestre(1)
, Antonio Díez(2)
, and Miguel V. Andrés(2)
1. Department of Optics, ICMUV, University of Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain.
2. Department of Applied Physics and Electromagnetisme, ICMUV, University of Valencia, Dr. Moliner 50,
46100 Burjassot, Valencia, Spain.
Abstract: The measurement of the modal index difference between the fundamental mode
and the first higher order modes in standard optical fibers, below and above cut-off, is used to
adjust the theoretical refractive index profile of the fiber. The main conclusion, in the case of
standard SMF-28e fiber, is that a step-index model for the core index profile is correct, but an
additional perturbation of the cladding refractive index profile is required.
The applications of few-moded optical fibers in space-division multiplexing, power amplifiers and sensors
are increasing significantly in the last years. In addition, a precise knowledge of high order cladding modes in
standard single mode fibers is important for a proper understanding of long period gratings design and
properties. Using an acousto-optic technique previously developed in our laboratory [1], we carried out a precise
and broadband characterization of LP1m modes dispersion curves, relative to the dispersion curve of the
fundamental mode LP01, in standard SMF-28e fiber. We assume that the dispersion curves measured in a broad
wavelength range should give enough information to work out fine details of the fiber refractive index profile.
The dispersion curves of fiber modes with an arbitrary refractive index profile were computed using a Fourier
based modal technique [2], previously developed in our research group. First, we postulated a simple step-index
model defined by a pure silica cladding of 125 m diameter, a Ge-doped core with a given numerical aperture
(NA = 0.120), and core radius a = 4.415 m. In our calculations, we include the material chromatic dispersion
[3]. We concluded that a step-index profile models precisely the dispersion curves bellow cut-off (in our case the
curve LP01-LP11 between 1 and 1.4 m, see Fig. 1 (b)), but the dispersion curves of cladding modes cannot be
adjusted correctly. In order to improve our model, we took into account the cladding perturbation reported in [4],
which origin is the thermal induced stress during the drawing process. This perturbation can be modeled with a
single parameter, n2 = 0.6510
-3, as defined in Fig. 1 (a). Using this parameter in combination with a step-index
profile for the fiber core, we obtain a good match between theory and experiment, as Fib. 1 (b) depicts.
Figure 1. (a) Relative permittivity profile. (b) Modal index difference between modes LP01 and LP1m of SMF-28e fiber:
experimental curves (red dashed line) and theory (solid blue line).
References
[1] E. Alcusa-Sáez, A. Díez, and M. V. Andrés, “Accurate mode characterization of two-mode optical fibers by in-fiber
acousto-optics”, Opt. Express 24, 4899 ( 2016).
[2] E. Silvestre, T. Pinheiro-Ortega, P. Andrés, J. J. Miret, and A. Ortigosa-Blanch, “Analytical evaluation of chromatic
dispersion in photonic crystal fibers”, Opt. Lett. 30, 453 (2005).
[3] J. W. Fleming, “Dispersion in GeO2-SiO2 glasses”, Appl. Opt. 23, 4486 (1984).
[4] G. Violakis, N. Aggarwal, and H. G. Limberger, “Stress changes in H2-loaded SMF optical fibers induced by cw-Ar+
244 nm irradiation”, Opt. Mat. Express 2, 1490 (2012).
Desarrollo de materiales híbridos para aplicaciones termoeléctricas
José F. Serrano-Claumarchirant1, Alvaro Seijas1, Anabel López1
1) Institut de Ciència dels Materials (ICMUV), Universitat de València, Catedrático José
Beltrán 2, 46980 Paterna, Valencia, Spain
*E-mail: [email protected], [email protected], [email protected]
En la actualidad hay una gran demanda de energía por parte de la sociedad, que debería provenir
de nuevas fuentes de energía renovable. La termoelectricidad se basa en la generación de
electricidad a partir de gradientes de temperatura, por tanto, nos permite aprovechar la energía
calorífica que está siendo desperdiciada. Para medir la eficiencia de los materiales
termoeléctricos se emplea la figura de mérito (ZT= S2σT/κ), donde S es el coeficiente de
Seebeck, σ la conductividad eléctrica, T la temperatura absoluta y κ la conductividad térmica
del material. Finalmente, en el caso de materiales con conductividades térmicas muy semejantes
se puede emplear también el factor de potencia (PF=S2σ). En este trabajo se han realizado tres
estudios.
Síntesis de telas termoeléctricas
En primer lugar, se depositaron nanotubos de carbono (CNTs)sobre la tela de fieltro utilizando la técnica de Layer-by-Layercon el fin de obtener un sustrato de fieltro conductor. Acontinuación, se sintetizó electroquímicamente PEDOT sobre latela de fieltro. Se determinó la conductividad, el coeficienteSeebeck y el Factor de Potencia de las telas.
Obtención de films transparentes de MWCNT
Con la intención de preparar films transparentes de nanotubosde pared múltiple (MWCNT) se prepararon dispersiones deMWCNT con diferentes proporciones de SDBS. Los films seobtuvieron mediante la técnica de spin coating. Además, seestudió el dopaje tipo n de los MWCNT añadiendo a lasdispersiones diferentes cantidades de PVP, PEI y PVA. Sedeterminó la conductividad, el coeficiente Seebeck y el Factorde Potencia de los films.
Obtención de films híbridos PEDOT-MWCNT
Para la obtención de films híbridos de PEDOT-MWCNT sesintetizaron nanopartículas de PEDOT funcionalizadas con PDDAy se prepararó una dispersión de MWCNT utilizando DOC comoestabilizador. Los films se obtuvieron mediante la técnica deLayer-by-Layer. Se determinó la conductividad, el coeficienteSeebeck y el Factor de Potencia de los films.
ESA/VSC Laboratorio Europeo de Materiales de Alta Potencia para el Espacio. Consorcio Espacial Valenciano
Rafael Mata Sanz1,2*, Benito Gimeno Martínez1,2
1) Institut de Ciència dels Materials (ICMUV), Universidat de València, Catedrático José Beltrán 2, 46980 Paterna,
Valencia, Spain
2) Val Space Consortium, ESA-VSC High Power Space Materials Laboratory, Escuela Técnica Superior de Ingeniería,
University of Valencia, Avenida de la Universidad s/n, 46100 Burjassot, Valencia, Spain.
*E-mail: [email protected]
Hoy en día, los satélites participan activamente en la vida social, tecnológica y científica. Todos los días la
humanidad hace uso de ellos, como por ejemplo: en meteorología, comunicaciones o sistemas de posicionamiento.
Para que todo esto sea posible, es necesario un control del tráfico de información mediante ondas de comunicación
entre los satélites y la tierra. Pero, las ondas que transportan esta información pueden interaccionar de forma
nociva con los propios componentes que conforman el satélite. En el ESA/VSC Laboratorio Europeo de
Materiales de Alta Potencia para Espacio [1] se investigan los diferentes procesos relacionados con la interacción
entre las ondas y los materiales que componen los distintos dispositivos instalados en los satélites.
Cuando los satélites son puestos en órbita, es necesario que todo el aire que queda atrapado en su interior se libere
antes de ser encendidos. Este proceso se conoce como venteo y/o desgasificado de un componente. Además, hay
muchos factores a tener en cuenta, como por ejemplo, la necesidad de que el material sea ligero, buen conductor,
entre otros. Por este motivo, un componente puede estar fabricado en un determinado material aislante de baja
densidad, pero a su vez estar recubierto por una fina capa de metal que mejore su respuesta eléctrica. Para ello se
realizan recubrimientos de metales sobre superficies. Finalmente, los electrones de los vientos solares, los
producidos por efecto fotoeléctrico o de los propios componentes del satélite pueden interaccionar con el campo
electromagnético de las ondas y ser acelerado hasta impactar con las paredes del material. Dependiendo de su
energía cinética, pueden suceder varios procesos: el primero es una retrodispersión elástica; por otra parte, pueden
ser absorbidos y, mediante colisiones con los átomos, ceder su energía por colisiones elásticas para volver a salir
del material; finalmente, la energía cedida puede arrancar electrones del material. Estos últimos corresponden a la
Emisión Secundaria de Electrones (SEY) que pueden ser acelerados nuevamente por la onda electromagnética
de comunicación; y así sucesivamente provocar la destrucción del dispositivo. La SEY depende fuertemente de
parámetros superficiales y de la temperatura y en este laboratorio se analizan todas esta propiedades de los
materiales que puedan afectar a las telecomunicaciones entre los satélites y la tierra.
[1] http://www.val-space.com/
Epitaxial graphene as Van der Waals substrate for GaN growth: structural and electrical characterization
O. Klymov1, Z. Seoudi2, N. Garro1, A. Cros1,*, M. Gruart3, N. Feldberg3 and B. Daudin3 1Institute of Materials Science (ICMUV), University of Valencia, PO Box 22085, E-46071,
Valencia, Spain 2Université Paris Sud, France
3Université Grenoble Alpes, CEA, INAC, F-38000 Grenoble, France
*E-mail: [email protected]
The integration of nitride semiconductor optoelectronic devices with graphene offers a wide range
of possibilities. Being only one atom thick, it is highly transparent and may be used as conductive
contact layer in deep-ultraviolet devices. Besides its flexibility and high thermal conductance,
graphene can be grown or deposited on many different platforms. It is however not yet clear how
the properties of graphene are affected by the growth of GaN by Molecular Beam Epitaxy. In
particular, a considerable damage of graphene has been reported [1] caused by the active
nitrogen species generated by the radio frequency N2 plasma source.
In this work we investigate epitaxial graphene grown on SiC that has been exposed to Ga and N
plasma. Four samples are investigated, including a graphene/SiC reference. Strain and doping of
the graphene layers have been analyzed by Raman scattering. The structural changes under the
different treatments are addressed by Atomic Force Microscopy (AFM), and correlated with the
electrical properties of the 2D layer by Kelvin Probe Force Microscopy (KPFM). The reference
sample consists mainly of one layer graphene (1LG), with some two layer graphene (2LG)
inclusions. Contrary to the results of Ref. [1], we observe that the graphene layer not only survives
N exposure, but also the dispersion of the Raman shift of these samples narrows considerably.
This narrowing is not observed in samples exposed only to Ga. KPFM maps allow the detail
identification of 1LG and 2LG and their correlation with changes in the topography. The results
obtained, supported by detailed Transmission Electron Microscopy images, point to the
intercalation of N and Ga species between graphene and SiC. Indeed, while in the reference
samples 2LG regions are higher than 1L graphene by 0.42 nm, in samples exposed to N or N and
Ga the topography is somewhat inverted: 1LG regions are higher than 2LG by 0.70-0.80 nm. This
height difference demonstrates that intercalation takes place at the interface between SiC and
graphene, leading to the full decoupling of the graphene from the SiC surface and improving strain
and doping homogeneity of graphene
[1] S. Fernández-Garrido et al., Nano Lett. 17, 5213 (2017).
Ring versus Fabry-Pérot Passive Mode-Locked Fiber Laser Set-Up
Antonio Carrascosa*, José L. Cruz, Antonio Díez and Miguel V. Andrés
Department of Applied Physics and Electromagnetism-ICMUV, University of Valencia, C/Dr. Moliner 50, Burjassot 46100, Spain
*E-mail: [email protected]
Mode-Locked Laser can generate short pulses (femtosecond to picosecond), an essential characteristic that makes the laser suitable for many applications such as material processing [1, 2], CARS microscopy, fluorescence lifetime imaging measurements, high-resolution LIDAR systems [2, 3] and supercontinuum source [4].
We are developing a passively mode-locked (ML) fiber laser oscillator where all components used are made in optical fiber. The active medium is an ytterbium doped fiber and the laser modulation is generated by a saturable absorbed. This work shows the oscillator main characteristics in Ring and Fabry-Pérot configuration. The study is focused on the laser stability, power and operation regime in both set-ups depending on applied pump power.
Figure 1: Ring oscillator set-up Figure 2: Fabry-Pérot oscillator set-up
The fundamental operation ML is proportional to the cavity length. The laser output power as a function of increasing pump power is shown in figure 3, with different laser ML regimes indicated. Moreover, the pulse energy is not lineal with the pump. Finally, the pulse width is studied in both arrangements as a function of increasing pump power. Figure 3: Oscillator Ring ML regime as a function of pump power.
[1] Rafael R. Gattass & Eric Mazur. Femtosecond laser micromachining in transparent materials. Nature Photonics 2, 219 - 225 (2008)
[2] Wei Shi, Qiang Fang, Xiushan Zhu, R. A. Norwood and N. Peyghambarian. Fiber lasers and their applications. APPLIED OPTICS, Vol. 53, No. 28, 1 October 2014
[3] Baumgartl M, Gottschall T, Abreu-Afonso J, Díez A, Meyer T, Dietzek B, Rothhardt M, Popp J, Limpert J, Tünnermann A. Alignment-free, all-spliced fiber laser source for CARS microscopy based on four-wave-mixing. Opt Express 20 (19). 2012
[4] Goëry Genty, Stéphane Coen, and John M. Dudley. Fiber supercontinuum sources. Vol. 24, No. 8, August 2007, J. Opt. Soc. Am.
50 100 150 200 250
Pump (mW)
0
2
4
6
8
10
Out
put (
mW
)
Q-S
witc
h M
L
ML
Ines
tabi
lity
ML
Q-S
witc
h M
L
2 x
puls
ing
Ines
tabi
lity
2 x
puls
ing
Tran
sitio
n 2
to 3
pul
ses
3 x
puls
ing
Tran
sitio
n 3
to 4
pul
ses
4 x
puls
ing
Crystalline-size Dependence of Dual Emission Peak on Hybrid Organic Lead
Iodide Perovskites Films at Low Temperature
Raquel Chulia-Jordan 1, *
, Elena Mas-Marzá2, Juan Martínez-Pastor
1
1)
Institut de Ciència dels Materials (ICMUV), Universitat de València, Catedrático José Beltrán 2,
46980 Paterna, Valencia, Spain 2)
Institute of Advanced Materials-Universitat Jaume I, 12003 Castelló, Spain
*E-mail: [email protected]
We have investigated the crystalline-size dependence of optical absorption and
photoluminescence emission of CH3NH3PbI3 films, which is necessary to identify the
potencial practical applications of the gadgets based on perovskite films. This study was
carried out at low temperatures to minimize the extra complexity induced by thermal effects.
The purpose was clarifying the origin of the dual emission peak previously reported in
literature[1]. We have found that the grain-size is responsible of the appearance or
disappearance of this dual emission on CH3NH3PbI3 at low temperatures, whereas we have
inferred that the thickness of the perovskite layer is a much more important factor than the
size of the grains in the location of the energy of the bandgap. Moreover, the increase in the
grain size allows slowing down the phase transition. Additionally, we evidence a decrease in
the effective Rydberg energy of the exciton in several samples, from 23-25 meV at 7 K to
12-13 meV at 165 K, by fitting to Elliot-Toyozawa theory. We have extracted other important
physical parameters of perovskites from the photoluminescence-data deconvolution, such as
bandgap, exciton–phonon interaction and exciton binding energy. A new phase transition at
45.5 K was determined by the temperature dependence of full width at half maximum and
integrated intensity of the photoluminescence, and it was confirmed by the radiative lifetime
obtained from the time-resolved photoluminescence emission by mean of time-correlated
single photon counting at different temperatures, excitation fluencies and emission energies.
Figure 1: Radiative (τr)
and non-radiative (τnr)
lifetime versus temperature
at different temperatures
for the excitation fluencies
of 370 nJ/cm2. Inset:
Structural stability of
CH3NH3PbI3 as a function of
temperature.
[1] Dar, M.I., et al., Origin of unusual bandgap shift and dual emission in organic-inorganic
lead halide perovskites. Sci. Adv., 2016. 2.
Structural and vibrational properties of GdVO4 under high pressure
T. Marqueño1,*
, D. Errandonea1, D. Santamaría-Pérez
1, D. Martínez-García
1, J. Pellicer-Porres
1, P.
Rodríguez-Hernández2, S. Radescu
2, A. Muñoz
2, C. Popescu
3, S. N. Achary
4, A. K. Tyagi
4
1Departamento de Física Aplicada, ICMUV, MALTA Consolider Team, Universitat de València, Valencia,
Spain
2Departamento de Física Fundamental II, and Instituto de Materiales y Nanotecnología, MALTA
Consolider Team, Universidad de La Laguna, Tenerife, Spain
3CELLS-ALBA Synchrotron Light Facility, Cerdanyola, 08290 Barcelona, Spain
4Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
* E-mail: [email protected]
Gadolinium vanadate (GdVO4) is a transparent crystal member of the AVO4 family with tetragonal
structure (S.G. 141 I41/amd) which is isostructural to zircon (ZrSiO4) [1]. Rare-earth orthovanadates have
been extensively studied under high pressure due to their multiple technological applications [2-4] and
several phase transitions have been reported [2-5]. Among the rare-earth vanadates, one of the less studied
compounds is GdVO4. This oxide has been studied only under non-hydrostatic conditions. Two phase
transitions have been observed below 30 GPa [6,8]. However, the high-pressure structural behavior of
rare-earth vanadates is extremely sensitive to non-hydrostaticity. In this context, we have studied GdVO4
under quasi-hydrostatic high pressure. We have performed x-ray diffraction and Raman spectroscopy
experiments in a diamond-anvil cell up to 30 GPa using neon as pressure-transmitting medium. In contrast
with previous studies, we have found only one phase transition. The crystal structure of the high-pressure
phase is found to be the tetragonal scheelite-type structure (S.G. I41/a No. 88). The equation of state, axial
compressibilities, and phonon frequencies under pressure are reported for the two phases of GdVO4 and
compared to other zircon-type vanadates. Ab initio total-energy DFT and lattice dynamics calculations are
also reported and compared with experimental results. Experiments and calculations provide quite
consistent results. The reported work contribute to improve the understanding of the behavior of
orthovanadates under strong compression.
Figure 1. Crystal structure
of zircon-type GdVO4.
Polyhedral units within the
unit-cell are shown.
References
[1] B. C. Chakoumakos, et al., J. Solid State Chem. 109, 197 (1994).
[2] D. Errandonea et al., Phys. Rev. 79, 184104 (2009).
[3] A. B. Garg et al., J. Phys.: Condens. Matter 26, 265402 (2014).
[4] C. Popescu et al., J. Phys.: Condens. Matter 28, 035402 (2016).
[5] D. Errandonea et al., Mater. Res. Bull. 50, 279 (2014).
[6] B. Yue, et al., Phys. Rev. Lett. 117, 135701 (2016).
[7] F. Hong, et al., Appl. Phys. Lett. 110, 021903 (2017).
[8] A. B. Garg et al., J. Phys.: Condens. Matter 29, 055401 (2017).
Coupled surface acoustic waves cavities
A. L. O. Bilobran1, M. M. de Lima1 and P. V. Santos2
1University of Valencia - Institute of Materials Sciences, Catedratico Augustin Escardino, 9, 46890Paterna, Valencia (Spain)
2Paul-Drude-Institut fur Festkrperelektronik, Hausvogteiplatz 57, D-10117 Berlin (Germany)
A few years ago it was demonstrated that fundamental effects of quantum-wave transport (Bloch oscil-lations, Wannier-Stark ladders and Landau-Zener tunneling) can be studied with surface acoustic waves(SAWs) propagating in 1D coupled acoustic cavities [1]. The coupled phononic cavities - a periodicarrangement of metal stripes within a surface acoustic delay line on piezoelectric substrate - impliesa local change in the SAW propagation properties, which results from the mechanical loading as wellas the screening of the piezoelectric potential underneath the metal stripes. Posteriorly, it was shownthat the acoustic field distribution can be electrically tuned by controlling the potential of the cavitieselectrodes [2]. The metallic stripes could be either electrically isolated from each other or short circuitedall together in order to control their acoustic properties. Changing from floating stripes, i. e., electri-cally isolated, to short circuited ones, the acoustic field changes due to the screening of the piezoelectricpotential underneath the stripes. Here, we discuss the two dimensional finite element model that wehave developed. The model describes fairly well the behavior of such devices without any adjustmentparameters. In it, the mechanics and electrostatics models are coupled to simulate the piezoelectricity.Using a frequency domain study the eigenfrequencies can be predicted with an accuracy of less then 1%.The transmission around them, in dB, is estimated with an error smaller than 10% for the short circuiteddevices, whereas for the floating ones the accuracy decreases. Moreover we calculate the variation ofparameters such as the stress, the strain and the displacement throughout the structures.
Fig. 1: (a) Micrograph of a sample with five coupled mi-crocavities (5C) defined by metal stripes forming Braggreflectors (BRs). The SAWs are excited by the inter-digital transducer IDT1 and detect after propagationthrough the MCs by IDT2. (b) Michelson interferom-eter used to probe the time-averaged squared amplitudeof the vertical particle displacement along the surface ofthe sample.
BR BR
S12
(dB
)
Frequency (MHz)320 340 360 320 340 360
0
0
0
0
0
0
0
0
-25
-25
-25
-25 -15
-15
-15
-15
Frequency (MHz)
S12
(dB
)
a) b)
1C
2C
5C
1C
2C
5C
Fig. 2: Experimental (solid lines) and calculated (dottedlines) transmission spectra for a set of grating structureswith floating (a) and short-circuited (b) stripes.
References
1. M. M. de Lima et al. Phys. Rev. Lett. 104, 165502 (2010).2. M. M. de Lima et al. Appl. Phys. Lett. 100, 261904 (2012).
1
Measurement of UV-induced losses in photosensitive fibers X. Roselló-Mechó, M. Delgado-Pinar, J.L. Cruz, A. Diez and M.V. Andrés
Department of Applied Physics and Electromagnetism (ICMUV), University of Valencia, C/ Dr. Moliner 50, 46100 Burjassot, Valencia, Spain
*E-mail: [email protected]
The most employed method to fabricate fiber Bragg gratings and long period gratings is the UV-assisted inscription of photosensitive fibers. The exposure of a fiber to UV-radiation induces a change in the refractive index, which is associated with a variation of the absorption coefficient, and may induce volume changes. In this work we present a technique to measure the increment of the absorption coefficient due to the fabrication process. The technique also allows to discriminate between the absorption and scattering contributions to the overall losses. The increment of the absorption coefficient is measured employing the thermal sensitivity of the whispering gallery modes (WGMs). A section of a UV-irradiated fiber plays the role of a microresonator. The WGM resonances are excited at a given point (axial resolution: 200 µm) using a 2 µm auxiliary tapered fiber, which can be swept along the resonator [1]. An infrared pump signal of moderate power (～1W) is used in order to measure the absorption coefficient through the temperature variation (detection limit: 0.03ºC). The thermal profile of an irradiated Fibercore PS980 (5 mm) illuminated with a signal at 1550 nm and 1 W is depicted in Fig. 1(a). We observed that the irradiated section suffers a higher temperature increment than the non-irradiated section. This is directly related with an increment of the ! . Following the analysis developed in [2], it is possible to relate the ratio between the temperature increment and the ratio of the absorption coefficients,! . The measured value of this ratio for the PS980 fiber is
for a UV-irradiation value of 150 J/mm2.
Fig. 1: (a) Typical thermal profile of an irradiated section of PS980. (b) Direct measurement of the losses as the fiber is irradiated (irradiated fiber length: 5 cm).
To discriminate the contribution between absorption and scattering contributions, the direct measurement of the total losses as the fiber was irradiated was carried out, Fig 1(b). While the WGM measurement gives information of the absorption coefficient, in this case, the measured losses take into account both absorption and scattering. For the PS980 fiber, the ratio of the losses is ! (the losses of the pristine fiber are 120 dB/km @1550 nm), where ! . By using the results of both measurements, we can calculate the value of the two coefficients: ! dB/km and ! dB/km.
[1] M. Delgado-Pinar, I. L. Villegas, A. Díez, J. L. Cruz, and M. V. Andrés, Opt. Lett. 39, 6277 (2014). [2] M. K. Davis, M. J. F. Digonnet, and R. H. Pantell, J. Light. Technol. 16, 1013 (1998)
αabs
ΔT2 /ΔT1 = αabs2 /αabs
1αabs
2 /αabs1 = 36.9 ± 0.7
α2 /α1 = 52 ± 3α = αabs + αscat
αabs2 = 3680 ± 20 αscat
2 = 2500 ± 400
Irradiatedsection
Temperaturetransient
z (mm)
(�C
/W) (a) (b) (c)
Lo
ss
(dB
)
Irradiance (J/mm2)
(a) (b) (c)
Effects in long period gratings due to high power pulse propagation. E. Rivera-Pérez, Antonio Díez, Antonio Carrascosa, Miguel V. Andrés.
Departamento de Física Aplicada - (ICMUV), Universitat de València, c/ Dr. Moliner 50, 46100 Burjassot, Valencia, Spain
*E-mail: [email protected]
A long period grating (LPG) basically is a periodic perturbation of the refractive index in the core of an optical
fiber. This periodic perturbation is generally of hundreds of microns and a length of a few centimeters, which leads to
the coupling between the fundamental and cladding modes. The LPG’s have been exploited for the development of
applications like sensors, communications, and optical signal processing among others. Recently, a significant
advance has been demonstrated in the manufacture of LPG’s in optical fibers with a sub-nanometer bandwidth [1]
made possible either enhanced their applications or make new applications. Particularly, for power applications, it is
necessary to investigate the effects that might occur. Here we study these effects focuses on the analysis of the
transmittance change of signal from probe laser when an intense pump pulse laser is propagated through the LPG
under test.
Fig. 1. (a) Experimental arrangement. (b) Changes in transmittance of the probe signal when a pulse propagates along the LPG. Probe
wavelength: 1555 nm (black), 1556.9 nm (dash line). Inset: Transmittance of LPG under test. (c) Transmittance of LPG under test (green), and
transmittance of LPG under test when an intense pulse is located at centre of the LPG (blue).
Fig. 1(a) shows the experimental setup. The pump laser employed as pumping of intense pulses was a Q-Switched
emitting at 1064 nm (0.7 ns duration pulses at 20 kHz repetition rate). The probe laser was a CW emitting in the
C-band. Both signals were combined-separated using beams combiner, a filter, and a 1064/1550 WDM coupler.
Additionally, a fiber polarization controller and a half wave plate were introduced to adjust the polarization state of
the beams. When pump laser propagates trough LPG an increase in the refractive index occurs due to the nonlinearity
of the fiber, which produces a deformation and a displacement of the notch towards longer wavelengths. This
behavior can be interrogated with the probe laser by tuning their wavelength to match the edges of the whole notch of
the LPG. The Fig. 1(b) shows the change in transmittance of the probe laser when the pump laser is propagated
through the LPG. Black and pink curves correspond to the specific case when the probe laser was tuned to the left and
right sides of the notch respectively, and the inset shows the transmission spectrum of the LPG. The resonance peak
is centered at 1556 nm and the -3dB bandwidth is 1.8 nm. By the changes in transmittance on whole resonance peak
is possible analyze the effects in the LPG due to high power pulse propagation like is showed in Fig. 1(c) where the
green and blue traces correspond to transmission spectrum of original LPG and when the pulse is located at centre of
the LPG, respectively.
[1] L. Poveda-Wong et al., Opt. Lett., 42, 1265 (2017).
1550 1552 1554 1556 1558 1560 1562
-20
-15
-10
-5
0
Tran
smitt
ance
(dB
)Wavelength (nm)
c)b)a)a)
1552 1554 1556 1558 15600.0
0.5
1.0
-2 -1 0 1 2 30.0
0.5
1.0
T
Wavelength (nm)
∆T
Time (ns)
a)
1370 1380 1390 1400 1410 1420 1430 1440 1450
(nm)
-4
-3
-2
-1
0
1
T (d
B)
Interacción acusto-óptica en fibra óptica de dos modos Saúl Rosales-Mendoza*, Martina Delgado-Pinar, A. Díez, Miguel V. Andrés Bou
1) Institut de Ciència dels Materials (ICMUV), Universitat de València, Catedrático José Beltrán 2, 46980 Paterna, Valencia, Spain. E-mail: [email protected]
La interacción acusto-óptica (IAO) consiste en la interacción de una onda acústica (OA) con una onda electromagnética (OEM). En nuestro caso, estudiaremos la IAO usando una fibra óptica de dos modos, que hace de guía óptica y acústica. La OA, al propagarse por la fibra, introduce una perturbación espacial en el índice de refracción. Esto induce el acoplamiento entre dos modos ópticos, siempre que se cumpla la condición de ajuste de fases (Eq. 1). En nuestro caso, el acoplamiento será entre el modo fundamental, LP01, y un modo de orden superior de índices nm:
𝜆𝜆𝑅𝑅 = 𝛬𝛬[𝑛𝑛01(𝜆𝜆) − 𝑛𝑛𝑛𝑛𝑛𝑛(𝜆𝜆)] (1) donde 𝜆𝜆𝑅𝑅 y 𝛬𝛬 son las longitudes de onda de la OEM y la OA respectivamente, y 𝑛𝑛01(𝜆𝜆) − 𝑛𝑛𝑛𝑛𝑛𝑛(𝜆𝜆) es la diferencia de índices efectivos entre los modos acoplados. El acoplamiento es sintonizable en longitud de onda variando la frecuencia 𝐹𝐹 de la onda acústica. Esto nos permite medir experimentalmente la curva de sintonización del acoplamiento λΡ vs. Λ (o F) y, a partir de ella, determinar experimentalmente la apertura numérica de la fibra, NA, y longitud de onda de corte del primer modo, λc. En nuestros experimentos se trabaja con el modo acústico fundamental de flexión. La simetría de la perturbación que este modo introduce en la fibra es tal que sólo permite el acoplamiento entre el modo fundamental LP01, de simetría par, y los primeros modos de simetría impar, los LP1m [1].
El montaje experimental empleado es igual al mostrado en [1]. La fibra estudiada fue la SM2000, que es monomodo a partir de ~1.7µm, según el fabricante. La longitud de interacción era de 80 cm, y la fuente de luz era un conjunto de LEDs entre 1.0 y 2.0 µm. El montaje permitía controlar la polarización de la luz a la entrada, y excitar únicamente el modo fundamental a la entrada de la región de interacción. El análisis de la luz a la salida se hizo con un analizador de espectros óptico y una cámara CCD. La Fig. 1 muestra un espectro de la luz a la salida para la frecuencia acústica 2.82 MHz, junto con los patrones del campo a la salida, a las longitudes de onda de resonancia. Los tres picos de atenuación corresponden a las resonancias de los acoplamientos del modo fundamental con los modos HE21, TE01 y TM01, los tres modos que componen el LP11. Cabe destacar que esta técnica permite resolver estos tres modos que normalmente aparecen solapados.
Figura 1. Espectro del acoplamiento LP01-LP11 para una frecuencia acústica de 2.82 MHz en la fibra SM2000.
La Fig. 2 muestra la curva de sintonización de la resonancia en el rango 1.0-2.0µm, para los modos LP11, LP12, LP13 y LP14. En el caso del primer modo, se observa un cambio de pendiente en la curva, relacionado con el hecho de que pasa de ser un modo confinado en el núcleo a ser un modo de cubierta. Este efecto no se observa en los otros tres modos, que siempre son de cubierta. A partir del ajuste de los cálculos teóricos (línea continua) a las medidas experimentales (puntos), puede determinarse la NA (0.1196) y la λc del LP11 (1.66 μm). Los parámetros obtenidos coinciden razonablemente con los proporcionados por el fabricante.
Referencias [1] E. Alcusa-Sáez, A. Díez, M. V. Andrés, “Accurate mode-characterization of two-mode optical fibers by in-fiber acousto-optics”, Opt. Express 24, p. 4899 (2016).
1 1.5 2 2.5 3 3.5
F (MHz)
1
1.5
2
(m
)
LP01-LP11
LP01-LP12
TM01 HE21
TE01
LP01-LP13 LP01-LP14
Figura 2. Curva de sintonización de las resonancias de la IAO para la fibra SM2000.
Combination of the atrane and Stöber method for the obtaining of
Mesoporous Materials Based on Silica and doped with different Metals
CAROLINA GARCÍA-LLACER, RAHMA HANY, JAMAL EL HASKOURI,
AURELIO BELTRÁN and PEDRO AMORÓS
Institut de Ciencia dels Materials (ICMUV), Universitat de València, PO Box 22085, 46071-Valencia
(Spain)
In recent decades the mesoporous silica have attracted great interest because of their
outstanding physical and chemical properties such as mechanical strength, chemical
stability or surface properties (other than their synthetic versatility)1.2
. Although initially
they were used in catalysis, thanks to some characteristics such as their high surface
area, morphology and low toxicity, their potential for many other applications and, in
particular, in the field of medicine, was quickly shown3,4
. These features allow the use
of mesoporous silica as potentially able to play a dual role of diagnosis and therapy
calling them as (theragnostic materials).
In 2000, the NANOMAT group of the Institute of Materials Sciences of the University
of Valencia developed a new model for the synthesis of mesoporous silicas, called the
atrane method5,6
. A great advantage of this synthesis method is its synthetic versatility,
since by carrying out different modifications we can obtained different types of
mesoporous silicas.
That said, in recent years, combining the atrane method with Stöber7 method we have
developed spheres mesoporous silica with different sizes doped with by several metals
such as Fe, Al, Co, Ti, in order to develop new teragnósticos materials.
These materials have been characterized by various techniques such as X-rays, nitrogen
adsorption-desorption, TEM, SEM.
Mesoporous silica doped by Fe obtained by combination by atrane y sober method
[1] Slowing I. I., Vivero-Escoto J. L., Trewyn B. G. & Lin V. S.-Y. J Mater Chem, 2010, 20,
7924-7937.
[2] Roggers R., Kanvinde S., Boonsith S & Oupický D. AAPS Pharm Sci Tech, 2014, 15, 1163-
1171.
[3] Vallet-Regi, M., Rámila A., del Real R. P. & Pérez-Pariente J. Chem Mater, 2001, 13, 308-
311.
[4] Zapotoczny B., Guskos N., Koziol J. J. & Dudek M. R. J Magn Mater, 2015, 374, 96-102.
[5] S. Cabrera, J. El Haskouri, C. Guillem, J. Latorre, A. Beltrán, D. Beltrán, M. D. Marcos, P.
Amorós, Sol. Stat. Sci., 2, 405 (2000)
[6] El Haskouri J., Cabrera S., Caldéz M., Alamo J., Beltrán A., Marcos M. D., Beltrán D. &
Amorós P. J Inor Mat, 2001, 3, 1157-1163.
[7] Stöber W., Fink A. & Bohn E. J Colloid Interface Sci, 1968, 26, 62-69.
Acoustically tuned dynamic wavelength division multiplexing devices
Dominik D. Bühler1*
, A. Crespo-Poveda1, A. Cantarero
2 and M. M. de Lima Jr.
1
1) Institut de Ciència dels Materials (ICMUV), Universitat de València, Catedrático José Beltrán
2, 46980 Paterna, Valencia, Spain
2) Instituto de ciencia molecular (ICMOL), Universitat de València, Catedrático José Beltrán 2,
46980 Paterna, Valencia, Spain
Phasar multiplexers based on arrayed waveguide gratings (AWG) are key components in
modern integrated photonic systems. Acoustically tuning these multiplexers enables robust,
compact and fast responding devices improving on recently demonstrated technology.
Different concepts will be presented in each of which a surface acoustic wave (SAW) is
induced in such a way that its propagation direction coincides perpendicularly with the AWG.
The WGs of this grating introduce dispersion and connect two multimode interference (MMI)
couplers of distinct lengths or free propagation regions (FPRs) of equal dimensions that are
employed as a power splitter and combiner, respectively. By tuning the SAW amplitude this
setup allows us to alter the refractive index in each arm discretely and, thus, introduce specific
phase shifts resulting in wavelength depended constructive interference at each of the outputs
of the combiner MMI or second FPR.
This mechanism can be readily applied for wavelength routing and circuit switching in optical
networking systems of essentially any material platform. The devices here are presented for
operation at the telecommunication wavelengths around 1.55 µm, working on a (Al,Ga)As
platform and tuned by a SAW in the low GHz range (Figure 1 and 2).
Figure 1 & 2 Concept design (left) and image (right) of an actual single multimode interference
(MMI) based modulator dynamically tuned by a focused surface acoustic wave (SAW) that enables
photonic rerouting of incoming light signals.
Versatility and Sustainability in the Development of Polyurethane Formulations
Manuel Asensio1, Juan F. Ferrer-Crespo
1, Ana C. Puig
1, Diana Favero
2, Rafael Muñoz-Espí
1,
Clara M. Gómez1
1) Institut de Ciència dels Materials (ICMUV), Universitat de València, 46980 Paterna, Spain.
2) Universidade de Caxias do Sul – RS, 95070-560 Caxias do Sul, RS – Brasil
*E-mail: [email protected], [email protected]
Thermoplastic polyurethanes (TPUs) are versatile materials used in diverse applications. Due
to their structure, segmented in phases, TPUs present specific mechanical, thermal, and
chemical properties, which depend on the molecular weight, the chemical nature of the raw
materials, and the synthesis method. The most common synthesis is the so-called prepolymer
method, based on a polyaddition reaction between a diisocyanate and a polyol, followed by
the reaction of the formed prepolymer with a diol for the chain extension until the
completeness of the reaction [1].
Polyurethanes synthesized in the absence of isocyanates have been widely studied in
academic research, but the industrialization of the corresponding processes has important
drawbacks, such as the toxicity of reagents or by-products, the low reactivity between the
cyclic carbonate/amine, and the low molecular weight. In this context, the synthetic route of
polyaddition between cyclic carbonate and amine represents a suitable pathway to avoid these
drawbacks, especially now that regulations on toxicity of chemicals are becoming stricter. In
particular, the reaction between bicyclic carbonates bCC5 synthesized from glycerol
carbonate (due to its easy and economical synthesis) and reactive diamines is a promising
route [2].
[1] J. O. Akindoyo, M. D. H. Beg, S. Ghazali, M. R. Islam, N. Jeyaratnam, and A. R. Yuvaraj,
“Polyurethane types, synthesis and applications-a review,” RSC Adv. 2016, 6,
114453–114482.
[2] L. Maisonneuve; O. Lamarzelle; E. Rix; E. Grau; H. Cramail. Isocyanate-Free Routes to
Polyurethanes and Poly(hydroxy Urethane)s. Chem. Rev. 2015, 115, 12407–12439.
Multifunctional Hybrid Colloids: Polymers and Inorganics Meet at the Nanoscale
Adrián Aguado-Hernándiz1, Amparo Sánchez-Soler
1, Ana Torres-Suay
1, Hilario Verdeguer-Asensio
1,
Olaia Álvarez-Bermúdez1,2
, Clara M. Gómez1, Francisco F. Pérez-Pla
1, Katharina Landfester
2,
Rafael Muñoz-Espí1,
* 1 Institut de Ciència dels Materials (ICMUV), Universitat de València, Paterna, Spain
2 Max Planck Institute for Polymer Research, Mainz, Germany
*E-mail: [email protected]
Even if the term “organic/inorganic hybrid nanomaterial” has become incredibly popular in
the last few decades, the combination of organic and inorganic matter at the nanoscopic scale
is not new. Indeed, nature has been fabricating hybrid materials since the origins of life. For
instance, bone, nacre, and corals are typical examples of this phenomenon. Inspired by nature,
chemists and materials scientists investigate the synergy between different organic and
inorganic building blocks to develop new materials. In this context, colloidal methods
represent a very convenient and versatile strategy for the preparation of novel hybrid
nanoparticles [1, 2].
In this poster, we will present four different —but closely related— topics under current
investigation by our team:
(1) Poly(methyl methacrylate) nanoparticles cross-linked by two different titanium
oxoclusters, with application in the catalytic oxidation of organic sulfides.
(2) Magnetoresponsive catalytic nanoparticles comprised of polystyrene and metal oxides
(TiO2 or CeO2, and Fe3O4), applied in the catalytic hydration of amides. Pickering
stabilization (i.e., the use of inorganic nanoparticles for the stabilization of emulsions)
is used for the nanoparticle synthesis.
(3) Thermal energy storage by encapsulation of phase change materials (PCMs) in either
polyurethane/inorganic or poly(methyl methacrylate) nanocapsules.
(4) Conducting hybrid nanoparticles of polyaniline or polypyrrole, incorporating CeO2 or
Fe3O4 nanoparticles, applied in the formation of films.
All four topics focus on the use of the so-called miniemulsion technique for the synthesis of
polymer–inorganic hybrid nanoparticles or nanocapsules.
[1] M. A. Hood, M. Mari, R. Muñoz-Espí. Materials 2014, 7, 4057–4087
[2] R. Muñoz-Espí, O. Álvarez-Bermúdez. In: D. J. McClements and S. M. Jafari (eds.).
Nanoemulsions: Formulation, Applications, and Characterization, pp. 477–515. Academic
Press-Elsevier, 2018.