Search results for "Fiber optic sensor"
showing 10 items of 62 documents
Wavelength-codified fiber laser hydrogen detector
2005
We report a scheme for an optical hydrogen detector that codifies the information in wavelength. The system is based on an erbium-doped fiber laser with two coupled cavities and a Palladium-coated tapered fiber within one of the laser cavities. The tapered fiber acts as the hydrogen-sensing element. When the sensing element is exposed to a hydrogen atmosphere, its attenuation decreases changing the cavity losses. This change leads the system to switch lasing from the wavelength of the auxiliary cavity to the characteristic wavelength of the cavity which contains the sensing element. The detection level can be shifted by adjusting the reflective elements of the cavity containing the sensing …
Vulnerability of OFDR-based distributed sensors to high γ-ray doses
2015
Vulnerability of Optical Frequency Domain Reflectometry (OFDR) based sensors to high γ-ray doses (up to 10 MGy) is evaluated with a specific issue of a radiation-hardened temperature and strain monitoring system for nuclear industry. For this, we characterize the main radiation effects that are expected to degrade the sensor performances in such applicative domain: the radiation-induced attenuation (RIA), the possible evolution with the dose of the Rayleigh scattering phenomenon as well as its dependence on temperature and strain. This preliminary investigation is done after the irradiation and for five different optical fiber types covering the range from radiation-hardened fibers to highl…
A frequency-output fiber optic voltage sensor with temperature compensation for power systems
2003
Abstract We present a frequency-output fiber optic voltage sensor for power systems with temperature compensated response. The sensor employs PZT-type ceramic tubes, which are interrogated by a length of single-mode fiber coiled onto the tubes and a Mach–Zehnder interferometer. The combination of piezoelectric tubes with properties exhibiting opposite behavior to temperature changes is successfully exploited to passively compensate the temperature sensitivity of the sensor. The prototype reported here exhibits a resolution of 13 mV rms and the deviations of the sensor’s response due to temperature changes are within 1% over the temperature range between −30 and 70 °C. The device presented h…
Passive compensation of the thermal drift of magnetostriction based Q-switched fiber lasers
2009
Abstract The authors propose and demonstrate a method to compensate the thermal drift of magnetostriction based Q-switched fiber lasers, which is caused by the eddy currents induced in the Terfenol-D magnetostrictive actuators. The consequent wavelength detuning between the fiber gratings of the laser is passively compensated by the use of Monel 400 as thermal actuator of the non-modulated grating. A highly stable pulsed signal is achieved in the range of 1 Hz–5 kHz, with a wavelength detuning between gratings maintained below 10 pm. Furthermore, an optimization of the use of the pump power is proposed, utilizing part of it for simultaneously pumping a fiber optic based amplification stage.
Novel in-line fiber-optic filters and polarisers
2005
Novel in-line devices, based on a tapered fiber whose uniform waist has been metal-coated, are reported. The resonant excitation of a surface plasma mode of the metal film allows for the design of wavelength filters and polarisers
Photonic-crystal fiber-based pressure sensor for dual environment monitoring.
2014
In this paper the development of a side-hole photonic-crystal fiber (SH-PCF) pressure sensor for dual environment monitoring is reported. SH-PCF properties (phase and group birefringence, sensitivity to pressure variations) are measured and compared to simulated data. In order to probe two environments, two sections of the SH-PCF with different lengths are spliced and set in a Solc filter-like configuration. This setup allows obtaining the individual responses of the first and second fiber independently, which is useful for a space-multiplexed measurement. As the employed fiber is sensitive to pressure variations, we report the use of this configuration for dual environment pressure sensing.
<title>Optical pressure sensor based on the side-emitting optical fiber</title>
2003
Two prototype models of pressure sensors using side-scattering optic fiber as the sensitive element have been designed and experimentally assessed. The study showed that the use of 600-micron silica core side-scattering fiber resulted in 5 to 6 times higher sensitivity compared to the oridinary PCS fibers.
Experiments with a fiber-based optical dipole trap for cold Cs-Atoms
2011
Pulling a standard optical fiber to a diameter of less than the wavelength of the guided light causes the light field to project slightly over the fiber boundaries in form of an evanescent wave. The latter can be used for light-matter-interactions in the vicinity of the surface of the fiber and therefore allows to perform quantum optic experiments.
Raman based distributed fiber optic temperature sensors for structural health monitoring in radiation environment
2015
Raman distributed temperature sensor (RDTS) measurements were performed during γ-radiation on three different classes of standard multimode fibers (pure, Ge-doped and F-doped). The sensor response is affected by the radiation induced attenuation phenomena leading to errors in the temperature measurements. The amplitude of this error strongly depends on the fiber type and the irradiation conditions. These results are promising in view of the integration of these RDTS into the deep geological repository for radioactive waste.
<title>Optical fiber loop sensors</title>
2003
Article presents prepared and tested constructions of loop hybrid fiber optical sensors with light amplitude modulation used for measuring loads and temperature.