INANOE Repositorio (Inst- Nacional de Astrofísica, Óptica y Electrónica
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Acousto-optical interaction and its advanced applications
Get PDFIn this this work, the acousto-optical interaction is studied. Since its
inception, in 1922, it has been widely studied and applied. Here, the
development of three advanced application of this branch of physics is
considered.
First, is analyzed the potential use of an acousto-optical cell for be included as
a dynamic diffraction grating, in order to improve in many ways the actual
static gratings used, in the Guillermo Haro astrophysical observatory. For
this, it was necessary to estimate the performance of several acousto-optical
materials available today.
Second, a specific mechanism of the acousto-optical nonlinearity is studied to
regulate the performance of the collinear acousto-optical filter. The theory of
this phenomenon is analyzed and confirmed experimentally using and
advanced filter based on calcium molybdate (CaMoO 4 ) single-crystal. The
transmission function of electronically tunable filter exhibits a dependence on
the applied acoustic power density, and as a result, it is possible to squeeze
the transmission function at the cost of decreasing the device efficiency
partially.
And at final, the triple product processor is studied for its potential
application in spectroscopy designed for 3-inch optics and analyzing all the
materials needed for its realization. The need to use 3-inch optics is mainly
oriented to exploit an acousto-optical cells with large aperture windows to get
a large time-bandwidth product
Sistema de adquisición de datos para la caracterización de fotomultiplicadores para experimentos de altas energías
Get PDFLos tubos fotomultiplicadores son sensores usados en los observatorios de rayos gamma debido a
su alta sensibilidad y respuesta temporal de unos cuantos nanosegundos. Para experimentos de altas
energías siguen siendo ampliamente utilizados. Los fotomultiplicadores necesitan ser calibrados y puestos
a trabajar con la misma sensibilidad, para ello se han utilizado sistemas de caracterización elaborados
por los grupos de trabajo donde ocupan este tipo de sensores.
El desarrollo de un sistema de caracterización de fotomultiplicadores ha surgido de la reciente necesidad
de contar con un sistema eficiente y confiable para determinar las características de los tubos
fotomultiplicadores. Debido a que actualmente en el mundo se están llevando a cabo importantes experimentos
para la detección de partículas de altas energías. México no es la excepción ya que en el
estado de Puebla se están construyendo dos observatorios y el Instituto Nacional de Astrofísica, Óptica
y Electrónica (INAOE) es una de las instituciones líder para su desarrollo. Los observatorios que se
está construyendo son High Altitude Water Cherenkov (HAWC) y Large Aperture GRB Observatory (LAGO).
Ambos son observatorios con detectores Cherenkov de agua. Por un lado HAWC es un observatorio
de rayos gamma ( γ) de gran apertura capaz de monitorear el cielo en el rango de energías de 100 GeV
a 100 TeV. LAGO, una colaboración de instituciones latinoamericanas, busca detectar Gamma Ray
Bursts (GRBs). El sitio elegido para instalar ambos observatorios es Sierra Negra con una diferencia de
altura de unos cientos de metros.
Para la creación del sistema de caracterización se utilizó una electrónica con dispositivos modulares
que utiliza un sistema de comunicación que favorece la transferencia de datos de manera eficiente y
rápida, por medio de protocolo de comunicación VERSA Module Eurocard (VME). Los dispositivos
utilizados son una fuente de alto voltaje, un tarjeta digitalizadora, un puente de USB y la caja donde
van todos los dispositivos. Para realizar la adquisición de datos y la configuración de los módulos se
desarrolló un programa en C++, además se creó otro programa para la traducción a datos de carga,
amplitud máxima y tiempos que tarda la señal en llegar al 50% y 90% de la carga total
Caracterización de sensibilidad y degradación de películas ultra-delgadas de Al2O3 y su aplicación en sensores de estado sólido sensibles a iones
Get PDFThe development of solid state chemical sensors has been remarkable since its introduction
in the early 70s. Nowadays, a big number of parameters, and specially the
pH, can be measured with these devices at a low cost and with high accuracy. These
sensing devices can be classified in three main branches: Ion Selective Field Effect
Transistors (ISFETs), Light Addressable Potentiometric Sensors (LAPS), and capacitive
Electrolyte-Insulator-Semiconductor (EIS) sensors [1].
Generally, the operation of these devices is based upon the EIS system in which the
chemical sensitivity depends on the potential variation at the electrolyte-insulator interface,
and this variation is caused by changes in the chemical composition of the analyte
and the insulator surface [1–4]. However, the chemical degradation of the sensing surface
and the conduction mechanisms of the EIS system lead to the temporal variation of
the chemical sensitivity, commonly known as Drift, and Hysteresis [5–7]. Being these
last two phenomena, along with the problem of device encapsulation and integration of
reference electrodes, the bigger back draw in the application of these sensors [1, 2].
Taking into account the chemical sensitivity, drift and hysteresis, as well as the sensor
and reference electrode monolithic integration, this thesis presents a capacitive EIS
sensors design, the characterization of CMOS technology ISFET sensors with on-chip
pseudo-reference electrodes, and the characterization of aluminum oxide films (Al2O3)
deposited by Atomic Layer Deposition (ALD), as an alternative for sensing layers .
The designed sensors present a novel capacitive configuration which makes the change
in the flat-band voltage VFB higher, and allows the study of the influence that the area, geometry and distance of the integrated reference electrodes to the sensing regions have
in the chemical sensitivity. Moreover, the characterization of the ISFETs shows that
it is possible to integrate sensors and the required elements for their operation using
a standard CMOS processes. Finally, the influence that the chemical and morphological
degradation of the Al2O3 films surface and bulk have in sensitivity, drift and hysteresis
of the sensors is characterized.El desarrollo de los sensores químicos de estado sólido ha sido notable desde su aparición a principios de los 70s. Hoy en día un gran número de parámetros, y en especial
el pH, pueden ser medidos con estos dispositivos a un bajo costo y con alta precisión.
Estos elementos sensibles pueden catalogarse en tres ramas principales: Transistores
de Efecto de Campo Sensibles a Iones (ISFETs), Sensores Potenciométricos Direccionables
por Luz (LAPS), y Sensores Capacitivos Electrolito-Aislante-Semiconductor
(EIS) [1].
En general, la operación de estos dispositivos está basada en el sistema EIS en el
cual la sensibilidad química depende del cambio de potencial en la interfase electrolito aislante,
y este cambio se debe a su vez a la variación de la composición química del
electrolito por analizar y la superficie del aislante [1–4]. Sin embargo, la degradación
química de la superficie del aislante sensible y los mecanismos de conducción a través
del sistema EIS llevan a la variación temporal de la sensibilidad química, comúnmente
llamado deriva, y a la histéresis [5–7]. Son estos últimos dos fenómenos, en conjunto
con el problema del encapsulado de los dispositivos y la integración de electrodos de
referencia, las mayores atenuantes en la aplicación de estos sensores [1, 2].
Tomando en consideración la sensibilidad química, la deriva e histéresis, así como
la integración de sensores y electrodos de referencia en el mismo chip, esta tesis presenta
el diseño de sensores capacitivos EIS, la caracterización de sensores ISFET con
pseudo-electrodos de referencia integrados, y la caracterización de películas sensibles
de óxido de aluminio (Al2O3) obtenidas por Depósito por Capas Atómicas (ALD) , como una alternativa a los dieléctricos sensibles depositados por métodos convencionales.
Los sensores diseñados presentan una configuración capacitiva novedosa que permite
que los cambios en el voltaje de banda plana VFB sean mayores, y permitirán el estudio
de la influencia que el área, la geometría y la distancia de los electrodos integrados a
las regiones sensibles tienen en la sensibilidad electroquímica. Por otra parte, la caracterización de los ISFETs demuestra que es posible la integración de sensores y los
elementos necesarios para su operación usando un proceso CMOS estándar. Finalmente,
se caracteriza la influencia que la degradación química y morfológica de la superficie
y cuerpo de las películas de Al2O3 tienen en la sensibilidad, deriva e histéresis de los
dispositiv
Photon transport in binary photonic lattices
Get PDFWe present a review on the mathematical methods used to theoretically study classical propagation and quantum transport in arrays of coupled photonic waveguides. We focus on analysing two types of binary photonic lattices where selfenergies or couplings are alternated. For didactic reasons, we split the analysis in classical propagation and quantum transport but all methods can be implemented, mutatis mutandis, in any given case. On the classical side, we use coupled mode theory and present an operator approach to Floquet-Bloch theory in order to study the propagation of a classical electromagnetic field in two particular infinite binary lattices. On the quantum side, we study the transport of photons in equivalent finite and infinite binary lattices by couple mode theory and linear algebra methods involving orthogonal polynomials. Curiously the dynamics of finite size binary lattices can be expressed as roots and functions of Fibonacci polynomials
A classical simulation of nonlinear Jaynes–Cummings and Rabi models in photonic lattices
Get PDFThe interaction of a two-level atom with a single-mode quantized field is one of the simplest models in quantum optics. Under the rotating wave approximation, it is known as the Jaynes-Cummings model and without it as the Rabi model. Real-world realizations of the Jaynes-Cummings model include cavity, ion trap and circuit quantum electrodynamics. The Rabi model can be realized in circuit quantum electrodynamics. As soon as nonlinear couplings are introduced, feasible experimental realizations in quantum systems are drastically reduced. We propose a set of two photonic lattices that classically simulates the interaction of a single two-level system with a quantized field under field nonlinearities and nonlinear couplings as long as the quantum optics model conserves parity. We describe how to reconstruct the mean value of quantum optics measurements, such as photon number and atomic energy excitation, from the intensity and from the field, such as von Neumann entropy and fidelity, at the output of the photonic lattices. We discuss how typical initial states involving coherent or displaced Fock fields can be engineered from recently discussed Glauber-Fock lattices. As an example, the Buck-Sukumar model, where the coupling depends on the intensity of the field, is classically simulated for separable and entangled initial states
Discrete-like diffraction dynamics in free space
No full textWe introduce a new class of paraxial optical beams exhibiting discrete-like diffraction patterns reminiscent to those observed in periodic evanescently coupled waveguide lattices. It is demonstrated that such paraxial beams are analytically described in terms of generalized Bessel functions. Such effects are elucidated via pertinent examples
OH Maser Sources in W49N: Probing Magnetic Field and Differential Anisotropic Scattering with Zeeman pairs using the VLBA
No full textOur analysis of a VLBA 12-hour synthesis observation of the OH masers in awell-known star-forming region W49N has yielded valuable data that enables usto probe distributions of magnetic fields in both the maser columns and the inter-vening interstellar medium (ISM). The data consisting of detailed high angular-resolution images (with beam-width ∼20 milli-arc-seconds) of several dozen OH maser sources or spots, at 1612, 1665 and 1667 MHz, reveal anisotropic scatter broadening, with typical sizes of a few tens of milli-arc-seconds and axial ratios between 1.5 to 3. Such anisotropies have been reported earlier by Desai, Gwinn & Diamond (1994) and interpreted as induced by the local magnetic field parallel tothe Galactic plane. However, we find a) the apparent angular sizes on the averagea factor of about 2.5 less than those reported by Desai et al. (1994), indicating significantly less scattering than inferred earlier, and b) a significant deviation inthe average orientation of the scatter-broadened images (by ∼10 degrees) from that implied by the magnetic field in the Galactic plane. More intriguingly, for afew Zeeman pairs in our set, significant differences (up to 6σ) are apparent in thescatter broadened images for the two hands of circular polarization, even when apparent velocity separation is less than 0.1 km s⁻¹. This may possibly be the first example of a Faraday rotation contribution to the diffractive effects in the ISM. Using the Zeeman pairs, we also study the distribution of magnetic field inthe W49N complex, finding no significant trend in the spatial structure function.In this paper, we present the details of our observations and analysis leading tothese findings, discuss implications of our results for the intervening anisotropic magneto-ionic medium, and suggest the possible implications for the structure of magnetic fields within this star-forming region
DIATOMIC ANALYTIC MOLECULAR PARTITION FUNCTIONS FOR STELLAR ATMOSPHERES
Get PDFApproximate partition functions and their derivatives for diatomic molecules are formulated taking into account the finite number of levels. A procedure is developed to derive compact analytic expressions, without free parameters, necessary for the efficient evaluation of some thermodynamic coefficients from the partition functions for diatomic molecules useful in modeling low temperature stellar atmo- spheres.Se formulan funciones de partición aproximadas y sus derivadas para moléculas diatómicas tomando en cuenta el número finito de niveles. Se desarrolla además un procedimiento para obtener expresiones analíticas compactas, sin parámetros libres, necesarias para la evaluación eficiente de algunos coeficientes termodinámicos de la función de partición para moléculas diatómicas de utilidad en el modelado de atmósferas estelares de baja temperatura
MILLIMETER AND SUBMILLIMETER COUNTERPARTS OF THE 2009 SEPTEMBER 26 SOLAR PROMINENCE
Get PDFWe present observations of the millimeter and submillimeter wavelength radio emission from an extended solar prominence. The data were obtained at the Solar Submillimeter Telescope (SST) during regular observation son 2009 September 26. The prominence signals were detected at 1.41 mm (212 GHz) and 0.74 mm (405 GHz) in an east-west raster practiced on the solar disk. Detection was confirmed by the He II image from the Extreme Ultraviolet Imaging Telescope of the Solar and Heliospheric Observatory (EIT/SOHO). The peak brightness temperature at the 1.41 mm and 0.74 mm are separatedby ∼4 arcmin with the 0.74 mm one closer to the solar limb. Assuming a free-free emission mechanism, both peak intensities correspond to an excess of brightness temperature of Tb ∼2×10³ K and they are consistent with an electron temperature and density of Te∼5.6 × 10³ K and ne∼ 10¹⁰ cm¯³, respectively.Presentamos observaciones en longitudes de onda milimétricas y submilimétricas de una prominencia solar extendida. Los datos fueron obtenidos en el Solar Submillimeter Telescope (SST) durante observaciones rutinarias el 29 de septiembre de 2009. Las radio señales fueron detectadas a 1.41 mm (212 GHz) y 0.74 mm (405 GHz) durante un barrido de este a oeste realizado sobre el disco solar. La detección fue confirmada por medio de la imagen de He II del Extreme Ultraviolet Imaging Telescope del Solar and Heliospheric Observatory (EIT/SOHO). Los máximos de las temperaturas de brillo a 1.41 mm y 0.74 mm están separados por ∼4 minutos de arco y la emisión a 0.74 mm es más cercana al limbo solar. Suponiendo un mecanismo de emisión del tipo libre-libre, ambos máximos corresponden a un exceso en la temperatura de brillo de Tb ∼2×10³ K, consistente con una temperatura y densidad electrónica de Te∼5.6 × 10³ K y ne∼ 10¹⁰ cm¯³, respectivamente
A massive bubble of extremely metal-poor gas around a collapsing Lyα blob at z = 2.54
Get PDFUsing long-slit optical spectroscopy obtained at the 10.4 m Gran Telescopio Canarias, we have examined the gaseous environment of the radio-loud quasar TXS 1436+157 (z = 2.54),previously known to be associated with a large Lyαnebula and a spatially extended Lyα-absorbing structure. From the Lyαnebula, we measure kinematic properties consistent withinfall at a rate of ∼10–100 M⊙ yr⁻¹ – more than sufficient to power a quasar at the top of theluminosity function.The absorbing structure lies outside of the Lyαnebula, at a radius of ≳40 kpc from thequasar. Against the bright unresolved continuum and line emission from the quasar, we detectin absorption the NVλλ1239, 1241, CIVλλ1548, 1551 and Si IVλλ1394, 1403 doublets, withno unambiguous detection of absorption lines from any low-ionization species of metal. Themetal column densities, taken together with the HI column density measurement from the literature, indicate that the absorbing gas is predominantly ionized by the quasar, has a massof hydrogen of ≳1.6 × 10¹¹ M⊙, a gas density of ≤18 cm⁻³, a line-of-sight thickness of≥18 pc and a covering factor approaching unity. While this absorbing structure is clearly notcomposed of pristine gas, it has an extremely low metallicity, with ionizationmodels providinga 3σ limit of 12+log(O/H) ≤ 7.3.To explain these results, we discuss a scenario involving starburst-driven superbubbles andthe creation of infalling filaments of cold gas which fuel/trigger the quasar. We also discussthe possibility of detecting large-scale absorbers such as this in emission when illuminated bya powerful quasar