A Novel Technique for Designing High Power Semiconductor Optical Amplifier (SOA)-Based Tunable Fiber Compound-Ring Lasers Using Low Power Optical Components

A simple, stable and inexpensive dual-output port widely tunable semiconductor optical amplifier (SOA)-based fiber compound-ring laser structure is demonstrated. This unique nested ring cavity enables high optical power to split into different branches where amplification and wavelength selection are achieved by using low-power SOAs and a tunable filter. Furthermore, two Sagnac loop mirrors, which are spliced at the two ends of the compound-ring cavity not only serve as variable reflectors but also channel the optical energy back to the same port without using any high optical power combiner. We propose and discuss how the demonstrated fiber compound-ring laser structure can be extended in order to achieve a high power fiber laser source by using low power optical components, such as N × N couplers and (N \u3e 1) number of SOAs. A coherent beam-combining efficiency of over 98% for two parallel nested fiber ring resonators is achieved over the C-band tuning range of 30 nm. Optical signal-to-noise ratio (OSNR) of +45 dB, and optical power fluctuation of less than ±0.02 dB are measured over three hours at room temperature

Métodos eléctricos, electroquímicos y espectrocópicos de detección para el tratamiento y eliminación de nitrato en el medio ambiente: revisión sistemática

El presente estudio tuvo como objetivo analizar cuáles son los aspectos a saber más relevantes de los métodos eléctricos, electroquímicos y espectroscópicos en la detección para el tratamiento y eliminación de nitrato en el medio ambiente; presentando una metodología de tipo aplicada donde se realizó la selección de 69 artículos científicos los cuales pasaron posteriormente a un proceso de inclusión y exclusión. Se obtuvo que, los métodos más usados son los métodos analíticos electroquímicos y quimio eléctricos, con un 74% para ambos casos, mientras que la técnica electroscópico se aplicó en un 26% de los estudios. Los materiales usados son los nanomateriales; además, los materiales como las nanopartículas de metal/óxido de metal, el grafeno, los de carbono, películas electropoliméricas y una amalgama de ellas; presentan propiedades como sus dimensiones en la nanoescala; el cual proporciona una mayor área de superficie para la interacción con el analito, mejorando la sensibilidad y la detección de concentraciones mínimas. La técnica que emplean los métodos se encargan de mejorar la estabilidad y la sensibilidad de los biosensores de nitrato. Siendo entre ellos los sensores electroquímicos, biosensores, espectroscópicos, eléctricos (quimiresistores, condensadores y transistores de efecto de campo) los que más se aplican

Characteristics of the Fiber Laser Sensor System Based on Etched-Bragg Grating Sensing Probe for Determination of the Low Nitrate Concentration in Water

The necessity of environmental protection has stimulated the development of many kinds of methods allowing the determination of different pollutants in the natural environment, including methods for determining nitrate in source water. In this paper, the characteristics of an etched fiber Bragg grating (e-FBG) sensing probe—which integrated in fiber laser structure—are studied by numerical simulation and experiment. The proposed sensor is demonstrated for determination of the low nitrate concentration in a water environment. Experimental results show that this sensor could determine nitrate in water samples at a low concentration range of 0–80 ppm with good repeatability, rapid response, and average sensitivity of 3.5 × 10−3 nm/ppm with the detection limit of 3 ppm. The e-FBG sensing probe integrated in fiber laser demonstrates many advantages, such as a high resolution for wavelength shift identification, high optical signal-to-noise ratio (OSNR of 40 dB), narrow bandwidth of 0.02 nm that enhanced accuracy and precision of wavelength peak measurement, and capability for optical remote sensing. The obtained results suggested that the proposed e-FBG sensor has a large potential for the determination of low nitrate concentrations in water in outdoor field work