Evaluation of 2.1µm DFB lasers for space applications

This paper presents the results obtained in the frame of an ESA-funded project called “Screening and Preevaluation of Shortwave Infrared Laser Diode for Space Application” with the objective of verifying the maturity of state of the art SWIR DFB lasers at 2.1µm to be used for space applications (mainly based on the occultation measurement principle and spectroscopy). The paper focus on the functional and environmental evaluation test plan. It includes high precision characterization, mechanical test (vibration and SRS shocks), thermal cycling, gamma and proton radiation tests, life test and some details of the Destructive Physical Analysis performed. The electro-optical characterization includes measurements of the tuning capabilities of the laser both by current and by temperature, the wavelength stability and the optical power versus laser current

DDS en el desarrollo de sistemas distribuidos heterogéneos con soporte para criticidad mixta

[Resumen] El uso de middleware de distribución facilita la programación de sistemas distribuidos heterogéneos, y por extensión también puede facilitar la generación automática de código como parte de una estrategia de desarrollo basada en modelos. Sin embargo, este middleware presenta una complejidad añadida que dificulta su uso en sistemas con ciertos requisitos de criticidad o de tiempo real. En este trabajo se hace una revisión de algunos estudios previos en los que se muestra la posibilidad de utilizar un middleware de distribución centrado en los datos (DDS, Data Distribution Service) para la integración de aplicaciones con criticidad mixta en sistemas distribuidos.Gobierno de España; TIN2014-56158-C4-2-P (M2C2

Mapping the Wigner distribution function of the Morse oscillator into a semi-classical distribution function

The mapping of the Wigner distribution function (WDF) for a given bound-state onto a semiclassical distribution function (SDF) satisfying the Liouville equation introduced previously by us is applied to the ground state of the Morse oscillator. Here we give results showing that the SDF gets closer to the corresponding WDF as the number of levels of the Morse oscillator increases. We find that for a Morse oscillator with one level only, the agreement between the WDF and the mapped SDF is very poor but for a Morse oscillator of ten levels it becomes satisfactory.Comment: Revtex, 27 pages including 13 eps figure

El uso de las nuevas tecnologías en la formación continua de los trabajadores en el sector papelero.

La clave del desarrollo industrial radica en que la formación debe desarrollarse a lo largo de toda la vida activa. Sin embargo, aunque esta necesidad de ampliar el acceso es reconocida por todos los actores implicados (institutos especializados en formación y la dirección de las empresas), hasta el momento se han producido escasos progresos debido a la ausencia de programas específicos de detección de necesidades formativas y metodologías concretas en la industria europea (en particular en la industria de la pasta y el papel). Movilidad, aprendizaje continuo y el uso de nuevos instrumentos tecnológicos obligan a alcanzar un mayor desarrollo de las cualificaciones laborales no sólo durante su etapa escolar sino a lo largo de la vida activa. Hoy día, aparecen nuevos campos de conocimiento en tecnología papelera que deben ser renovados en periodos de tiempo cada vez menores. Ciertos se definen en términos de conocimientos fundamentales (idiomas, informática, economía, etc.) y técnicos o profesionales (contabilidad, calidad, medio ambiente, etc.). El uso de nuevas herramientas formativas con capacidad de renovación (como los CD-Rom o la formación interactiva por Internet) permitirá una inmediata mejora de las cualificaciones de los empleados, en contraste con los diplomas que pierden su valor con el paso del tiempo.The key point is that access to training should be developed throughout life. While the need for such access is recognised by everybody, specialised institutes and the business sector alike, until now, there has been little progress in this area due to the absence of specific detection programmes and methodologies in the European chemistry industry (specially in the pulp and paper industry). Mobility, lifelong learning and the use of new technological instruments. It is necessary to achieve a higher develop of personal skills not only during the compulsory schooling but also through the working life. In these days, emerging particular knowledge fields in paper technology, production systems or business culture that should be renewal in periods of time that become shorter each time. Some of them are defined in terms of fundamental (languages, maths, law, computers, economics, etc.) or technical or vocational (accounting, quality, environment, etc.) knowledge. The use of new training tools easily renewable as the CD-ROM, Internet,... could allow an immediate improvement of people’s qualifications throughout their lives, in contrast to diplomas which lose their values as years go by

Dynamical characterization of monolithic MOPAs emitting at 1.5 μ�m

Eye-safety requirements in important applications like LIDAR or Free Space Optical Communications make specifically interesting the generation of high power, short optical pulses at 1.5 um. Moreover, high repetition rates allow reducing the error and/or the measurement time in applications involving pulsed time-of-flight measurements, as range finders, 3D scanners or traffic velocity controls. The Master Oscillator Power Amplifier (MOPA) architecture is an interesting source for these applications since large changes in output power can be obtained at GHz rates with a relatively small modulation of the current in the Master Oscillator (MO). We have recently demonstrated short optical pulses (100 ps) with high peak power (2.7 W) by gain switching the MO of a monolithically integrated 1.5 um MOPA. Although in an integrated MOPA the laser and the amplifier are ideally independent devices, compound cavity effects due to the residual reflectance at the different interfaces are often observed, leading to modal instabilities such as self-pulsations

Analysis of mode competition in a monolithic master- oscillator power‐amplifier emitting at 1.5 μm

The optical and radio-frequency spectra of a monolithic master-oscillator power-amplifier emitting at 1.5 ?m have been analyzed in a wide range of steady-state injection conditions. The analysis of the spectral maps reveals that, under low injection current of the master oscillator, the device operates in two essentially different operation modes depending on the current injected into the amplifier section. The regular operation mode with predominance of the master oscillator alternates with lasing of the compound cavity modes allowed by the residual reflectance of the amplifier front facet. The quasi-periodic occurrence of these two regimes as a function of the amplifier current has been consistently interpreted in terms of a thermally tuned competition between the modes of the master oscillator and the compound cavity modes

Collisional Semiclassical Aproximations in Phase-Space Representation

The Gaussian Wave-Packet phase-space representation is used to show that the expansion in powers of $\hbar$ of the quantum Liouville propagator leads, in the zeroth order term, to results close to those obtained in the statistical quasiclassical method of Lee and Scully in the Weyl-Wigner picture. It is also verified that propagating the Wigner distribution along the classical trajectories the amount of error is less than that coming from propagating the Gaussian distribution along classical trajectories.Comment: 20 pages, REVTEX, no figures, 3 tables include

Two-dimensional carrier density distribution inside a high power tapered laser diode

The spontaneous emission of a GaAs-based tapered laser diode emitting at lambda = 1060 nm was measured through a window in the transparent substrate in order to study the carrier density distribution inside the device. It is shown that the tapered geometry is responsible for nonuniform amplification of the spontaneous/stimulated emission which in turn influences the spatial distribution of the carriers starting from below threshold. The carrier density does not clamp at the lasing threshold and above it the device shows lateral spatial hole-burning caused by high stimulated emission along the cavity center. (C) 2011 American Institute of Physics. (doi: 10.1063/1.3596445

Simulation of facet heating in high-power red lasers

A two-dimensional self-consistent laser model has been used for the simulation of the facet heating of red emitting AlGaInP lasers. It solves in the steady-state the complete semiconductor optoelectronic and thermal equations in the epitaxial and longitudinal directions and takes into account the population of different conduction band valleys. The model considers the possibility of two independent mechanisms contributing to the facet heating: recombination at surface traps and optical absorption at the facet. The simulation parameters have been calibrated by comparison with measurements of the temperature dependence of the threshold current and slope efficiency of broad-area lasers. Facet temperature has been measured by micro-Raman spectrometry in devices with standard and non absorbing mirrors evidencing an effective decrease of the facet heating due to the non absorbing mirrors. A good agreement between experimental values and calculations is obtained for both devices when a certain amount of surface traps and optical absorption is assumed. A simulation analysis of the effect of non absorbing mirrors in the reduction of facet heating in terms of temperature, carrier density, material gain and Shockly-Read-Hall recombination rate profiles is provided