Fiber optic sensor

About: Fiber optic sensor is a research topic. Over the lifetime, 33562 publications have been published within this topic receiving 470059 citations.

Fiber Optic Bragg Grating Sensors

Abstract: This paper describes a new method that we have developed to generate Bragg grating filters in germania-doped communication fibers and discusses their applications as sensors. The gratings are formed by exposing a short section of the core, through the side of the fiber, to an interference pattern of intersecting coherent beams of UV light. A permanent periodic index modulation is produced by the interference fringes. It forms a phase grating which acts as a band rejection filter, passing wavelengths that are not in resonance with the grating and strongly reflecting wavelengths which satisfy the Bragg condition. The grating wavelength is sensitive to changes temperature and strain. Measurements of the shift in Bragg wavelength with these quantities are reported and compared with computed estimates of the sensitivity. A large number of independent gratings can be easily written along a length of fiber to make a distributed sensor system. We have also demonstrated that Bragg gratings can wavelength tune laser diodes, which could be used for detecting the wavelength shift of the Bragg sensors.

Ultra-low-loss optical fiber nanotapers

Abstract: Optical fiber tapers with a waist size larger than 1microm are commonplace in telecommunications and sensor applications. However the fabrication of low-loss optical fiber tapers with subwavelength diameters was previously thought to be impractical due to difficulties associated with control of the surface roughness and diameter uniformity. In this paper we show that very-long ultra-low-loss tapers can in fact be produced using a conventional fiber taper rig incorporating a simple burner configuration. For single-mode operation, the optical losses we achieve at 1.55microm are one order of magnitude lower than losses previously reported in the literature for tapers of a similar size. SEM images confirm excellent taper uniformity. We believe that these low-loss structures should pave the way to a whole range of fiber nanodevices.

Fiber Optic Sensors

Abstract: Fiber optic sensors have become indispensable tools for biomedical study because of their unique features such as (1) high sensitivity, (2) small footprint and endoscopic compatibility, (3) multiple agent distributive sensing capability, and (4) immunity from electromagnetic interference. In this chapter, we will provide a brief overview on the basic principle of fiber optic sensors, types of fiber optic sensors, and their applications to biomedical sensing. As a result of the page limitation, important work in this area may not be included in this chapter. Readers may find those contents in the listed reference material. Keywords: fiber optic sensors; light; sensing mechanism; biomedical sensing

A review of distributed optical fiber sensors for civil engineering applications

Abstract: The application of structural health monitoring (SHM) systems to civil engineering structures has been a developing studied and practiced topic, that has allowed for a better understanding of structures’ conditions and increasingly lead to a more cost-effective management of those infrastructures In this field, the use of fiber optic sensors has been studied, discussed and practiced with encouraging results The possibility of understanding and monitor the distributed behavior of extensive stretches of critical structures it’s an enormous advantage that distributed fiber optic sensing provides to SHM systems In the past decade, several R & D studies have been performed with the goal of improving the knowledge and developing new techniques associated with the application of distributed optical fiber sensors (DOFS) in order to widen the range of applications of these sensors and also to obtain more correct and reliable data This paper presents, after a brief introduction to the theoretical background of DOFS, the latest developments related with the improvement of these products by presenting a wide range of laboratory experiments as well as an extended review of their diverse applications in civil engineering structures

Tilted fiber Bragg grating sensors

Abstract: Optical fiber gratings have developed into a mature technology with a wide range of applications in various areas, including physical sensing for temperature, strain, acoustic waves and pressure. All of these applications rely on the perturbation of the period or refractive index of a grating inscribed in the fiber core as a transducing mechanism between a quantity to be measured and the optical spectral response of the fiber grating. This paper presents a relatively recent variant of the fiber grating concept, whereby a small tilt of the grating fringes causes coupling of the optical power from the core mode into a multitude of cladding modes, each with its own wavevector and mode field shape. The main consequence of doing so is that the differential response of the modes can then be used to multiply the sensing modalities available for a single fiber grating and also to increase the sensor resolution by taking advantage of the large amount of data available. In particular, the temperature cross-sensitivity and power source fluctuation noise inherent in all fiber grating designs can be completely eliminated by referencing all the spectral measurements to the wavelength and power level of the core mode back-reflection. The mode resonances have a quality factor of 105, and they can be observed in reflection or transmission. A thorough review of experimental and theoretical results will show that tilted fiber Bragg gratings can be used for high resolution refractometry, surface plasmon resonance applications, and multiparameter physical sensing (strain, vibration, curvature, and temperature).