Search results for "Optoelectronics"
showing 10 items of 2306 documents
Bloch Modes Coupling in Photonic Crystal Waveguides
2005
We investigate the properties of Bloch modes inside a photonic crystal waveguide. By using simultaneously a near field optical microscope and a transmittance setup, we demonstrate that Bloch modes having different parity are coupled.
Back-scattering of whispering-gallery-modes resonances of cylindrical microcavities: Refractometric applications
2009
Whispering-gallery modes (WGM) resonances of microcapillaries are directly compatible with microfluidic systems and have demonstrated its suitability for refractometric applications [1]. Microcapillaries with a submicrometric wall exhibit very large wavelength shifts as a function of the refractive index of the liquids that fill the inside of the capillary [2]. The spatial separation between the surface where the total internal reflection takes place (the outer surface) and the sensing surface (the inner surface) where the wave interacts with the analyte is a unique property that can be exploited to deal with analytes with a refractive index higher than that of the capillary [2].
Refractometric sensor based on whispering-gallery modes of thin capillarie.
2009
Whispering-gallery modes resonances of submicron wall thickness capillaries exhibit very large wavelength shifts as a function of the refractive index of the medium that fills the inside. The sensitivity to refractive index changes is larger than in other optical microcavities as microspheres, microdisks and microrings. The outer surface where total internal reflection takes place remains always in air, enabling the measure of refractive index values higher than the refractive index of the capillary material. The fabrication of capillaries with submicron wall thickness has required the development of a specific technique. A refractometer with a response higher than 390 nm per refractive ind…
A Compact SPICE Model for Organic TFTs and Applications to Logic Circuit Design
2016
This work introduces a compact DC model developed for organic thin film transistors (OTFTs) and its SPICE implementation. The model relies on a modified version of the gradual channel approximation that takes into account the contact effects, occurring at nonohmic metal/organic semiconductor junctions, modeling them as reverse biased Schottky diodes. The model also comprises channel length modulation and scalability of drain current with respect to channel length. To show the suitability of the model, we used it to design an inverter and a ring oscillator circuit. Furthermore, an experimental validation of the OTFTs has been done at the level of the single device as well as with a discrete-…
Frequency-modulation spectroscopy with blue diode lasers
2000
Frequency-modulation spectroscopy provides ultrasensitive absorption measurements. The technique is especially adaptable to diode lasers, which can be modulated easily, and has been used extensively in the near-infrared and infrared spectral regions. The availability of blue diode lasers now means that the accessible wavelength region can be increased. We successfully demonstrate wavelength-modulation spectroscopy and two-tone frequency-modulation spectroscopy for the weak second resonance line of potassium at 404.8 nm and for the transition at 405.8 nm in lead, starting from the thermally populated 6p(2) P-3(2) metastable level, information on the modulation parameters is obtained with a f…
Violet Diode Laser in Time-Resolved Stored-Ion Spectroscopy
2004
Lifetime measurements of the metastable 3d D-2(3/2) level in singly charged calcium were performed using the newly developed violet diode laser operated in an external cavity arrangement. The laser was employed on stored ions at the CRYRING facility to optically pump the resonance line at 397 nm. In combination with laser probing at 866 nm this detection scheme gave the possibility to record the lifetime of this level. which has a radiative lifetime of about 1 s.
Characterization of dual-polarization analogue radio over fiber fronthaul for LTE C-RAN architecture
2016
En este artículo se presentan los resultados de la medición ampliada de la radio analógica de doble polarización (DP) sobre fibra (RoF) en una arquitectura de red de acceso radio en la nube (C-RAN) de evolución a largo plazo (LTE). Esta técnica se propone para las conexiones de fibra entre las oficinas centrales y las estaciones base remotas. Se investigan varias longitudes de fibra óptica para determinar el mejor rendimiento del sistema en términos de magnitud de vector de error (EVM) y tasa de error de bit. La distancia máxima alcanzada para el caso de un ancho de banda LTE de 20 MHz es de 50 km, mostrando un valor de EVM admisible del 8,5% a la frecuencia de radio de 2,6 GHz cuando se ut…
Stretched fibre based dispersion compensating module for ultra high-speed telecommunication systems
2008
International audience; In this work, the potential efficiency of a low-loss, tunable second-and third-order dispersion compensating module based on a stretched optical fibre for ultra high-speed telecommunication systems is analysed. Experimental results at a repetition rate of 640 GHz show that precise dispersion compensation could be achieved in the range of +0.038 ps/nm by means of an 11.3 cm maximum stretching of a 48 m long dispersion compensating.
Practical design rules for single-channel ultra high-speed dense dispersion management telecommunication systems
2009
International audience; In this work, we establish some efficient and practical design rules for the implementation of single-channel ultra-high speed (>160-Gbit/s) telecommunication systems based on dense dispersion management. Moreover, we analyze some of actual implementation issues such as slope compensation scenario, junction losses, polarization mode dispersion and chromatic dispersion fluctuations.
Nanofilm metal layers as vacuum quality sensors
2010
Abstract A monitoring device for vacuum quality is realized by lowest cost single use oxygen sensors for vacuum insulation panels. They use the pressure dependence of oxide layer growth thickness on electrically measured metal nanofilms. These films were manufactured by e-beam evaporation, characterized in terms of resistance change with subsequent modeling of underlying mechanisms.