Feasibility study of a fiber ring laser working on the SLM regime in a BOTDA sensor

A feasibility study of the employment of a fiber laser working as the laser source of a Brillouin distributed sensor is presented in this paper. The erbium fiber ring laser structure designed works on the single longitudinal mode regime. The main parameters of the ring cavity are analyzed in terms of the laser requirements and the performance of a Brillouin optical time domain analysis sensor using the fiber laser as light source.This work was supported by the Spanish Government and FEDER funds under Project TEC2016-76021-C2-2-

Rapid clonal analysis of recurrent tuberculosis by direct MIRU-VNTR typing on stored isolates

<p>Abstract</p> <p>Background</p> <p>The application of molecular tools to the analysis of tuberculosis has revealed examples of clonal complexity, such as exogenous reinfection, coinfection, microevolution or compartmentalization. The detection of clonal heterogeneity by standard genotyping approaches is laborious and often requires expertise. This restricts the rapid availability of <it>Mycobacterium tuberculosis </it>(MTB) genotypes for clinical or therapeutic decision-making. A new PCR-based technique, MIRU-VNTR, has made it possible to genotype MTB in a time frame close to real-time fingerprinting. Our purpose was to evaluate the capacity of this technique to provide clinicians with a rapid discrimination between reactivation and exogenous reinfection and whether MIRU-VNTR makes it possible to obtain data directly from stored MTB isolates from recurrent episodes.</p> <p>Results</p> <p>We detected differences, between the MIRUtypes of recurrent isolates in 38.5% (5/13) of the cases studied. These included cases of i) exogenous reinfection, often with more resistant strains, ii) likely examples of microevolution, leading to the appearance of new clonal variants and iii) a combination of microevolution, coinfection and competition.</p> <p>Conclusion</p> <p>MIRU-VNTR rapidly obtained clinically useful genotyping data in a challenging situation, directly from stored MTB isolates without subculturing them or purifying their DNA. Our results also mean that MIRU-VNTR could be applied for easy, rapid and affordable massive screening of collections of stored MTB isolates, which could establish the real dimension of clonal heterogeneity in MTB infection.</p

High-temperature distributed sensor system via BOTDA and multimode gold-coated fiber

A high-temperature distributed sensor solution based on a Brillouin Optical Time Domain Analyzer and a multimode gold-coated fiber is presented and experimentally validated in this paper. Distributed temperature measurements up to 600°C will be demonstrated.This work has been supported by the Universidad de Cantabria and by the Spanish Ministerio de Ciencia e Innovación through project TEC2013-47264-C2-1-R

Electro-optic correlator for large-format microwave interferometry: Up-conversionand correlation stages performance analysis

In this paper, a microwave interferometer prototype with a near-infra-red optical correlator is proposed as a solution to get a large-format interferometer with hundreds of receivers for radio astronomy applications. A 10 Gbits/s Lithium Niobate modulator has been tested as part of an electro-optic correlator up-conversion stage that will be integrated in the interferometer prototype. Its internal circuitry consists of a single-drive modulator biased by a SubMiniature version A (SMA) connector allowing to up-convert microwave signals with bandwidths up to 12.5 GHz to the near infrared band. In order to characterize it, a 12 GHz tone and a bias voltage were applied to the SMA input using a polarization tee. Two different experimental techniques to stabilize the modulator operation point in its minimum optical carrier output power are described. The best achieved results showed a rather stable spectrum in amplitude and wavelength at the output of the modulator with an optical carrier level 23 dB lower than the signal of interest. On the other hand, preliminary measurements were made to analyze the correlation stage, using 4f and 6f optical configurations to characterize both the antenna/fiber array configuration and the corresponding point spread function.This work was supported by the Ministerio de Economía y Competitividad, Spain, under the Plan Nacional de I+D+i project with Reference No. ESP2015-70646-C2-1-R cofinanced with EU FEDER funds and the CONSOLIDER INGENIO 2010 programme under the Reference No. CSD2010-00064. The authors would like to thank Félix Gracia from Instituto Astrofísico de Canarias (IAC) for his assistance and help

Single longitudinal mode fiber ring laser

In this work, a dual-wavelength fiber ring laser working on the SLM regime is proposed and experimentally verified. A proof-of-concept device has been tested employing high precision small-sized SLM fiber lasers to complement the feedback produced by a passive FBG. The ring laser output inherits the spectral benefits of its SLM seed lasers but maintaining some power-related properties of ring cavities. These spectral benefits can also be achieved for a single wavelength, simplifying the requirements regarding power equalization between different wavelengths to obtain the SLM regime. The experimental results exhibit a remarkably good wavelength stability and SLM operation of a fiber ring laser with several meters of cavity length, both with single and multi-wavelength configurations.This work has been supported by the project TEC2016-76021-C2-2-R of the Spanish Government cofunded by EU/FEDER funds. Special thanks to Fibercore for their support

Feasibility study of strain and temperature discrimination in a BOTDA system via artificial neural networks

Automatic discrimination between strain and temperature in a Brillouin optical time domain analyzer via artificial neural networks is proposed and discussed in this paper. Using a standard monomode optical fiber as the sensing element, the ability of the proposed solution to detect the known changes that the Brillouin gain spectrum exhibits depending on the applied temperature and/or strain will be studied. Experimental results, where different simultaneous strain and temperature situations have been considered, will show the feasibility of this technique.This work has been supported by the projects TEC2013-47264-C2-1-R and TEC2016-76021-C2-2-R

Distributed high-temperature optical fiber sensor based on a Brillouin optical time domain analyzer and multimode gold-coated fiber

A high-temperature distributed sensor system based on a Brillouin optical time-domain analyzer and a multimode gold-coated fiber is presented in this paper. Distributed measurements of temperatures up to 600 °C are demonstrated with a temperature accuracy of about 10 °C. The system shows a consistent response for repetitive measurements, even considering increasing or decreasing temperature changes. This is the first time to the best of our knowledge that a gold-coated fiber is used for high-temperature distributed measurements in a Brillouin-based system. The proposed solution via the gold-coated fiber allows a feasible deployment in field applications such as industrial scenarios.This work was supported in part by the Spanish Government through Projects under Grant TEC2013-47264-C2-1-R and Grant TEC2016-76021-C2-2-R and in part by a Parliament of Cantabria postdoc Grant

Fiber Bragg Grating sensors for on-line welding diagnostics

In this work Fiber Bragg Grating transducers (FBGs) are used to perform an on-line monitoring of an arc-welding process by means of the combined temperature and strain profile. The main goal of this approach is to establish a correlation between the appearance of defects in the seams and the response offered by the FBGs, exploring the optimal disposition of the FBGs in terms of their sensitivity to weld defects. The proposed solution will be explored by means of welding tests and a comparison with a plasma spectroscopic analysis.This work has been supported by the project TEC2010-20224-C02-02 and grant AP2009-1403. Authors would also like to thank Roberto Perez Sierra for his valuable help during the FBGs fabrication process

Experimental demonstration of a Brillouin optical frequency-domain reflectometry (BOFDR) sensor

To measure the strain and/or temperature along an optical fiber with one-end access, a Brillouin optical frequency-domain reflectometry (BOFDR) technique is presented in this paper. It is based on detecting the spontaneous Brillouin scattering from a sinusoidally modulated pump light. Compared to the Brillouin optical frequency-domain analysis (BOFDA), this new BOFDR sensor approach presents the advantage that the measurements are free from the distorting components related to acoustic wave modulation, thus simplifying the associated data processing.This work has been supported by the projects MIUR-PON03PE_00155_1-OPTOFER and MIUR-PON03PE_00171_1-GEOGRID of the Italian government, and by the project TEC2013-47264-C2-1-R and TEC2016-76021-C2-2-R of the Spanish government

Simultaneous temperature and strain discrimination in a conventional BOTDA via artificial neural networks

A system based on the use of artificial neural networks allowing discrimination of strain and temperature in a conventional Brillouin optical time domain analyzer setup is presented and demonstrated in this paper. This solution allows to perform an automatic discrimination of both parameters without compromising the complexity or cost of the interrogation unit. The classification results, achieved by considering a preprocessing stage with dimensionality reduction via principal component analysis and spatial filtering, improve those obtained in a previous feasibility study.This work was supported in part by the Projects TEC2013-47264-C2-1-R and TEC2016-76021-C2-2-