Current Issue : October - December Volume : 2015 Issue Number : 4 Articles : 6 Articles
We designed a novel core-suspended capillary fiber that the core was suspended in the air\nhole and close to the inner surface of the capillary, and experimentally demonstrated its fabrication\ntechnology. In addition, a method for linking a single mode fiber and a core-suspended fiber was\nproposed based on splicing and tapering at the fusion point between the two fibers. By combining\nwith the optical time domain reflecto meter technology, we constructed a distributed gas sensor\nsystem to monitor greenhouse gas based on this novel fiber....
An all-metal 3-component optical fiber seismometer was proposed and experimentally demonstrated. The theoretical analysis was given based on the electro-mechanical theory. Calibration results showed that the axis sensitivity was about 41 dB (re: 0 dB=1 rad/g) with a fluctuation Ã?±2 dB in the frequency bandwidth of 5 Hzââ?¬â??400 Hz. A transverse sensitivity of about ?40 dB was achieved. The fluctuation of the acceleration sensitivity for the three accelerometers in the seismometer was within Ã?±2.5 dB. The minimum phase demodulation detection accuracy of the phase-generated carrier (PGC) was 10?5 rad/?Hz, and the minimum detectable acceleration was calculated to be 90 ng/?Hz....
A fiber-optic Fabry-Perot hydrogen sensor was developed by measuring the fringe contrast\nchanges at different hydrogen concentrations. The experimental results indicated that the sensing\nperformance with the Pd-Y film was better than that with the Pd film. A fringe contrast with a\ndecrease of 0.5 dB was detected with a hydrogen concentration change from 0% to 5.5%. The\ntemperature response of the sensor was also measured....
Liquid sealing is an effective method to convert a fiber-optic refractometer into\na simple and highly sensitive temperature sensor. A refractometer based on the thin-core\nfiber modal interferometer is sealed in a capillary tube filled with Cargille oil. Due to the\nthermo-optic effect of the sealing liquid, the high refractive-index sensitivity refractometer is\nsubsequently sensitive to the ambient temperature. It is found that the liquid-sealed sensor\nproduces a highest sensitivity of 2.30 nm/�°C, which is over 250 times higher than its\nintrinsic sensitivity before sealing and significantly higher than that of a grating-based fiber\nsensors. The sensing mechanisms, including the incidental temperature-induced strain effect,\nare analyzed in detail both theoretically and experimentally. The liquid sealing technique is\neasy and low cost, and makes the sensor robust and insensitive to the surrounding refractive\nindex. It can be applied to other fiber-optic refractometers for temperature sensing....
The growing interest in the development of smart textiles for medical applications\nis driven by the aim to increase the mobility of patients who need a continuous monitoring\nof such physiological parameters. At the same time, the use of fiber optic sensors (FOSs) is\ngaining large acceptance as an alternative to traditional electrical and mechanical sensors for\nthe monitoring of thermal and mechanical parameters. The potential impact of FOSs is\nrelated to their good metrological properties, their small size and their flexibility, as well as\nto their immunity from electromagnetic field. Their main advantage is the possibility to use\ntextile based on fiber optic in a magnetic resonance imaging environment, where standard\nelectronic sensors cannot be employed. This last feature makes FOSs suitable for monitoring\nbiological parameters (e.g., respiratory and heartbeat monitoring) during magnetic resonance\nprocedures. Research interest in combining FOSs and textiles into a single structure to\ndevelop wearable sensors is rapidly growing. In this review we provide an overview of the\nstate-of-the-art of textiles, which use FOSs for monitoring of mechanical parameters of\nphysiological interest. In particular we briefly describe the working principle of FOSs\nemployed in this field and their relevant advantages and disadvantages. Also reviewed are\ntheir applications for the monitoring of mechanical parameters of physiological interest....
We propose an optical spatial filter (OSF) method to suppress beam wander and spatial noise effects. Signal from random\ndisplacements of the focus spot around the optical axis within the constricted area is collected. This method advantageously\nsuppresses fluctuations in signal intensity.The OSF consists of a pinhole and cone reflector.The pinhole produces Fresnel diffraction\non the focus spot. The cone reflector provides directed reflectance onto the pinhole for random focus spot displacements due to\nbeam wander. The calculations of signal power are based on fluctuations of signal intensity that are minimized by the circular\naperture function of the pinhole and the cosine of the reflectance angle from the cone reflector.The method is applied to free-space\noptical communications at a wavelength of 1.55 ????m with an atmospheric chamber to provide optical propagation media. Based\non calculations, the beam wander angles that can be received by the OSF are from 14.0? to 28.0?. Moreover, based on experiment,\nthe OSF with a pinhole diameter of 20.0 ????m and cone reflector diameter of 1.5mm produces signal power of ?15.3 dBm. Both\ncalculations and experiment show that the OSF enhances the received signal power in the presence of turbulence....
Loading....