Fiber Bragg grating Research Papers (original) (raw)
We combine fiber Bragg grating (FBG) technology with a wet chemical etch-erosion procedure and demonstrate two types of refractive index sensors using single-mode optical fibers. The first index sensor device is an etch-eroded single FBG... more
We combine fiber Bragg grating (FBG) technology with a wet chemical etch-erosion procedure and demonstrate two types of refractive index sensors using single-mode optical fibers. The first index sensor device is an etch-eroded single FBG with a radius of 3 μm, which is used to measure the indices of four different liquids. The second index sensor device is an etch-eroded fiber Fabry-Pérot interferometer (FFPI) with a radius of ~1.5 μm and is used to measure the refractive indices of isopropyl alcohol solutions of different concentrations. Due to its narrower resonance spectral feature, the FFPI sensor has a higher sensitivity than the FBG sensor and can detect an index variation of 1.4×10-5. Since we can measure the reflection signal, these two types of sensors can be fabricated at the end of a fiber and used as point sensors.
The concept of structural health monitoring has been the subject of research over the last few years, particularly in civil and structural engineering where ageing infrastructure is of major concern. These studies have led to initiatives... more
The concept of structural health monitoring has been the subject of research over the last few years, particularly in civil and structural engineering where ageing infrastructure is of major concern. These studies have led to initiatives towards the development and deployment of new sensing technologies. Owing to the harsh environments found in the construction industry, and the large size of civil engineering structures, such sensors should be robust, rugged, easy to use and economical. Fiber Bragg grating (FBG) sensors offer a viable such sensing approach with a number of advantages over traditional sensors. These include immunity to electromagnetic interference, light weight, small size, multiplexing capabilities, ease of installation and durability. This paper reports some results from a multi-disciplinary research program on FBG sensors involving the School of Civil and Structural Engineering and the School of Electrical and Electronic Engineering at Nanyang Technological University in Singapore. Novel FBG strain sensors have been developed and deployed on highway bridges to measure dynamic strain, static strain, and temperature. Results of these studies indicate that, if properly packaged, FBG sensors can survive the severe conditions associated with the construction environments of civil infrastructure.
In recent years, fiber Bragg gratings (FBGs) are becoming increasingly attractive for sensing applications in biomechanics and rehabilitation engineering due to their advantageous properties like small size, light weight,... more
In recent years, fiber Bragg gratings (FBGs) are becoming increasingly attractive for sensing applications in biomechanics and rehabilitation engineering due to their advantageous properties like small size, light weight, biocompatibility, chemical inertness, multiplexing capability and immunity to electromagnetic interference (EMI). They also offer a high-performance alternative to conventional technologies, either for measuring a variety of physical parameters or for performing high-sensitivity biochemical analysis. FBG-based sensors demonstrated their feasibility for specific sensing applications in aeronautic, automotive, civil engineering structure monitoring and undersea oil exploration; however, their use in the field of biomechanics and rehabilitation applications is very recent and its practicality for full-scale implementation has not yet been fully established. They could be used for detecting strain in bones, pressure mapping in orthopaedic joints, stresses in intervertebral discs, chest wall deformation, pressure distribution in Human Machine Interfaces (HMIs), forces induced by tendons and ligaments, angles between body segments during gait, and many others in dental biomechanics. This article aims to provide a comprehensive overview of all the possible applications of FBG sensing technology in biomechanics and rehabilitation and the status of ongoing researches up-to-date all over the world, demonstrating the FBG advances over other existing technologies.
A fiber optic sensor using the first and the second order fiber Bragg grating spectra to simultaneously measure temperature and strain is investigated. A theoretical model for estimating the wavelength and the reflectivity of the second... more
A fiber optic sensor using the first and the second order fiber Bragg grating spectra to simultaneously measure temperature and strain is investigated. A theoretical model for estimating the wavelength and the reflectivity of the second order Bragg resonance in a fiber grating is developed, and the results are compared with the experimental results in Corning SMF 28 fiber. Moreover, technical issues regarding the sensor design such as the spectral characteristics of the Bragg gratings, bending loss in optical fibers and the higher order propagation modes are investigated. Experiments are conducted to measure the strain and temperature response of the grating sensors and compared to conventional sensors with encouraging results.
We report on a detailed study of the inscription and characterization of fiber Bragg gratings (FBGs) in commercial step index polymer optical fibers (POFs). Through the growth dynamics of the gratings, we identify the effect of UV-induced... more
We report on a detailed study of the inscription and characterization of fiber Bragg gratings (FBGs) in commercial step index polymer optical fibers (POFs). Through the growth dynamics of the gratings, we identify the effect of UV-induced heating during the grating inscription. We found that FBGs in annealed commercial POFs can offer more stable short-term performance at both higher temperature and larger strain. Furthermore, the FBGs' operational temperature and strain range without hysteresis was extended by the annealing process. We identified long-term stability problem of even the annealed POF FBGs.
We present a photosensitive three-hole microstructured optical fiber specifically designed to improve the refractive index sensitivity of a standard fiber Bragg grating (FBG) sensor photowritten in the suspended Ge-doped silica core. We... more
We present a photosensitive three-hole microstructured optical fiber specifically designed to improve the refractive index sensitivity of a standard fiber Bragg grating (FBG) sensor photowritten in the suspended Ge-doped silica core. We describe the specific photowriting procedure used to realize gratings in such a fiber. We then determine their spectral sensitivity to the refractive index changes of material filling the holes surrounding the core. The sensitivity is compared with that of standard FBGs photowritten in a six-hole fiber with a larger core diameter. We demonstrate an improvement in the sensitivity by two orders of magnitude and reach a resolution of 3 x 10(-5) and 6 x 10(-6) around mean refractive index values of 1.33 and 1.40, respectively.