Radio-frequency ring resonators for self-referencing fiber-optic intensity sensors

A theoretical and experimental study of radiofrequency ring resonators (RR) for referencing and improving the sensitivity of fiber-optic intensity sensors (FOS) is reported. The separation between lead and transducer losses in the FOS is solved by converting the light intensity fluctuations to be measured into RR losses that produce high amplitude variations in the proximity of the RR resonance frequencies. Two different self-referencing techniques are developed. Via the definition of the measurement parameter RM , sensor linearity and sensitivity are analyzed. A calibration using an optical attenuator is reported to validate the model.Publicad

Ring Resonators with Sagnac Loops for Photonic Processing in DWDM Backbone Networks

In this paper, optical configurations based on ring resonators (RR) with an internal Sagnac (SG) loop in the feedback path, are analyzed in terms of their amplitude response and dispersive properties for filtering and chromatic dispersion managing in digital transmission systems over amplified single- mode fiber (SMF) spans in DWDM backbone networks. Design issues for the architecture as regards quadratic dispersion and magnitude distortion are provided. The RR+SG compound filter provides frequency tunability of the amplitude and dispersion peaks by adjusting a coupling coefficient of an optical coupler, with no need for using integrated thermo-optic nor current- injection based phase shifters. The configuration can be employed as an additional structure for a general RR-based design and synthesis architecture, allowing bandwidth increase of dispersion compensators and flexibility. The performance of a compound filter consisting of a two RR in series stage and a RR+SG filter are reported as a more compact and effective solution for existing multi-channel SMF backbone links operating at high bit rates. Design guidelines of an integrated ring resonator based on polymer technology for showing feasibility of the proposal is reported.This work was partially supported by Spanish CICYT (TEC2006-13273-C03-03-MIC), European project NoE EPhoton/One+, CAM (FACTOTEM-CM:S-0505/ESP/000417), FENIS-CCG06-UC3MITIC-0619.Publicad

CWDM self-referencing sensor network based on ring resonators in reflective configuration

A new scalable self-referencing sensor network with low insertion losses implemented in Coarse Wavelength Division Multiplexing (CWDM) technology is reported. It allows obtaining remote self-referenced measurements with a full-duplex fibre downlead up to 35 km long, with no need for optical amplification. Fibre Bragg gratings (FBG) are used in order to achieve a reflective configuration, thus increasing the sensitivity of the optical transducers. Low-cost off-the-shelf devices in CWDM technology can be used to implement and scale the network. Ring resonator (RR) based incoherent interferometers at the measuring points are used as selfreferencing technique. A theoretical analysis of power budget of the topology is reported, with a comparison between the proposed network and a conventional star topology. Finally, the new configuration has been experimentally demonstrated.This work has been supported by CICYT:TIC2003-03783, UC3M:FAVICOBIS and CAM:FACTOTEM-CM (S-0505/ESP/000417).Publicad

Multi-sensor system using plastic optical fibers for intrinsically safe level measurements

A system for measuring liquid level in multiple tanks using optical fibe technology has been developed. Oil fiel service industry or any sector requiring liquid level measurements in flammabl atmospheres can be benefite from this intrinsically safe technology. The device used a single lens for the emitting and receiving fibe and it is based on amplitude variations as a function of the liquid distance and not in time of fligh or phase detection. Being the firs fiber-opti liquid level sensor with those characteristics for long ranges (>200 cm). A simple model to describe their behavior has been derived and tested on two prototypes. A Monte-Carlo method is used to fi the experimental data and obtain the model parameters. High accuracy between experimental data and fitte curve is obtained. The prototypes have a good linearity, better than 1.5% FS (full scale). Sensor heads are made of plastic optical fiber (POF) that are easy to handle, flexible and economical. They are excited by 650 nm lasers, housed in ST-connectors to obtain compact and rough prototypes. Optical multiplexing is used to increase the measuring safety area. Frequency division multiplexing is used to address each sensor head. A discussion about the influenc of tilts and aberrations is also included.Publicad

Spectroscopic trends for the determination of illicit drugs in oral fluid

The present work aims to review all of the articles published so far, focusedon the determination of drugs of abuse in oral fluid. This fluid provides a simpler,faster, and more controllable sampling in comparison with the other biological fluids,such as blood or urine. Actually, the main goal of the researchers is to lower the limitof detection (LOD) to detect quantities of drugs smaller than the cut-off limitsestablished by law for drug controls. Advances in Raman, infrared (IR), and nuclearmagnetic resonance (NMR) spectroscopy applications are discussed. SurfaceenhancedRaman spectroscopy (SERS) has been shown as the most sensitive techniquefor the detection of illicit drugs in oral fluid. The use of IR spectroscopy fordetermining drugs of abuse in oral fluid is growing, although the LODs obtained untilnow do not yet satisfy the necessities in the forensic field. Finally, NMR spectroscopyhas seldom been used to determine drugs in oral fluid. Another future trend seems tobe related with the use of portable instrumentation, which would allow us to performin-situ analysis. This last application seems to be particularly promising to performroadside drug tests and to identify overdose drugs in patients in emergency conditions

Analysis of street cocaine samples in nasal fluid by Raman spectroscopy

The principal objective of this work was to demonstrate the capability of Raman spectroscopy to detectsmall amounts of cocaine in nasal fluid, and to identify the main drug and the most widely used cuttingagents. Initially, standard samples were analysed and sampling conditions were studied by comparingdifferent swabs used for the sample collection. Once the most appropriate swab was selected, whichpermitted a relatively simple detection of the standard cocaine hydrochloride, qualitative analyses of realsamples were carried out. Three street cocaine samples were analysed, and the presence of cuttingsubstances was highlighted by the appearance of different bands not corresponding to the ones of thestandard cocaine. To identify the substances present in each sample, the spectra of the street cocainesamples were collected and compared with a digital library created on purpose with the spectra of themost common cutting agents. In this case, correlation coefficients permitted to recognize the most importantsubstances presumably present in the samples, and gave an estimation of the purity of the cocaine.However, when nasal fluid was present, its strong signal could overlap or interfere with thesmaller signal of the cutting substances, hindering their identification

Self-Referencing Fiber-Optic Intensity Sensors Using Ring Resonators and Fiber Bragg Gratings

An improved ring resonator self-referencing technique in a new reflection configuration for remote fiber-optic intensity sensors is demonstrated using fiber Bragg gratings. Sensor sensitivity doubles and a single fiber lead is used. The sensor is interrogated at two subcarrier frequencies having a high rejection of interference from laser source intensity fluctuations and loss in the fiber lead. We experimentally demonstrate the efficiency of the new reflection configuration, the usefulness of the theoretical model proposed, and discuss design parameters for optimum insertion lossesThis work was supported in part by CICYT (TIC2003-03783 and TEC2006-13273-C03-03-MIC), in part by UC3M (FAVICOBIS), in part by CAM (FACTOTEM-CM:S-0505/ESP/000417), and in part by COST 299.Publicad

Factores psicológicos vulnerabilidad a las lesiones deportivas : un estudio futbolistas

The main focus of this study was to analyze the different psychological factors considered important in explaining the risks of injury that professional and semi-professional soccer players are exposed to while playing their sport.Two hundred seventy-eight soccer players were the object of study. One questionnaire was used to evaluate psychological factors and another was used to collect data on injuries soccer players had suffered in the last three years. The results indicate that concentration is a variable that discriminates meaningfully between injured and uninjured soccer players. An evaluation of sport performance showed a meaningful relationship to very severe injures within the group of injuredplayers, it also showed a trend towards statistical significance between self-confidence and anxiety variables and the total number of injures

Calidad de vida y deporte : ¿conceptos siempre compatibles? : incidencia y manejo del estrés en deportistas

Intentamos en este trabajo contrastar la relación existente entre calidad de vida y deporte, partiendo de la revisión de los trabajos que recientemente han investigado en esta dirección. Así, comparamos las conclusiones que los diferentes estudios indica entre la mejora de la calidad de vida a partir de la realización de una práctica deportiva sistemática, y los componentes motivacionales que están en el origen de las personas que se inician en esta práctica. Precisamos que la no adaptación de ambos intereses (programas de actividad física y deporte con motivaciones para su realización puede ocasionar diferentes alteraciones, entre otras estrés). Se realiza a continuación una descripción de los diferentes.In this work, we try to show the relationship between life quality and sport, beginning from the works that have recently researched in this direction. In this way, we compare the conclusions that the different studies suggest between the improvement of the life quality beginning from the realization of a sistematic sport practice and the motivational components which are in the origin of people who initiate themselves into this practice. Likewise, we determine that when both interests (sport and physic activity programs and motivations for its realization) don't meet, different alterations can appear, stress for instance. Later, we realize a description of different predictors that can be in the origin of stress, as well as more adequate strategies for its intervention and prevention

Chemical classification of new psychoactive substances (NPS)

This work comprehensively reviews some fundamental concepts about drugs, especially focusing on new psychoactive substances (NPS), and their typical classifications based on either their effects (hallucinogens, stimulants or depressants), their origin (natural, synthetic, or semisynthetic), or legal situation (lawful, illicit, or unregulated). These classifications are highly useful in the medicine/legal field, but completely useless for the chemical determination of drugs. Hence, a classification of NPS based on their chemical composition is revised and discussed. This classification seeks to merge those recent and dispersed chemical groupings of NPS found in scientific literature and/or health/drugs reports from World/European/American Institutions facing the illicit use of drugs (WHO, UNODC, EMCDDA, OEDA, DEA, etc.) into a unique general classification, which might be useful for every forensic practitioner/researcher dealing with the identification of new psychoactive substances