Experimental setup for current measurement and a novel signal detection method for demodulation of fiber Bragg grating wavelength shift are developed. Being attached respectively on the upper and lower surface of a pendulum-type cantilever element, only a couple of matched FBGs are used for both current sensing and wavelength shift signal demodulating. So, the received light power will change due to the split of the two reflected spectrum of FBGs, which is corresponding to the electromagnetic force caused by the measured current. In addition, cross-sensitivity effect of FBG-based sensor automatically solved due to a differential signal process method. Static and quasistatic measurement results indicate the feasibility of the developed sensor system. Measurement error of

The last decade has been of great significance for the development of slow light technology. Electromagnetically induced transparency (EIT), coherent population oscillation (CPO), stimulated Brillouin scattering (SBS), stimulated Raman scattering (SRS), soliton collision, and photonic crystal waveguides have been used to slow down the velocity of light. In this paper, some important theoretical and technical developments of slow light technology that occurred over the last decade are discussed. Novel technologies for slowing down the velocity of light and their primary applications are introduced in detail. In addition, the future developing trends of slow light and its potential applications, especially in optical fiber sensors, are also forecasted and proposed in this paper.

Based on near-infrared spectral absorption and fiber-optic sensor technology, an experimental setup for low-water-content measurement of crude oil is developed. The advantages of this method include fast measurement, high accuracy, keeping the measured oil free of pollution, and being suitable for long-term on-line continuous monitoring. This technology can be used for those applications that require high-quality water-in-oil measurement and process control. The measurement resolution for water content is better than 0.005% in the range from zero to 2% by volume. Measurement errors are estimated to be

This paper describes an optical-fiber sensor developed for temperature measurement under the offshore oil well conditions. The sensor exploits the displacement of the optical absorption edge occurring in semiconductors under the influence of temperature variation as a result of temperature-induced energy shifting of conduction band extrema. The structure of the sensor and the measurement principle are described. The common-path reference measurement and node type error compensation technologies are developed. And the detailed theoretical analysis indicates that the proposed sensor system can effectively improve measurement errors caused by light fluctuation, difference and variation of the detector responsiveness, circuit magnification times, and so on. It approves that this sensor system can be applied under the long-term formidable conditions with fairly good measurement stability.