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Friebele EJ Putnam MA Patrick HJ Kersey AD Greenblatt AS Ruthven GP Krim MH Gottschalck KS 《Optics letters》1998,23(3):222-224
We report ultrahigh-sensitivity static strain sensing (noise equivalent strain =1.5n rms) by two fiber etalon cavities made from silica and fluoride fibers. The anomalous thermo-optic coefficient of fluoride glass fibers allows for determination of thermal and laser drift. This sensor is also capable of simultaneous strain and temperature measurement, with errors in strain and temperature of 6.4% and 0.68%, respectively. 相似文献
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A fiber Bragg grating sensor array is interrogated by use of a passively mode-locked fiber laser source. A novel demodulation scheme that uses highly dispersive fiber to convert the grating wavelength shift to a temporal shift in the arrival time of the reflected pulses is demonstrated. The source bandwidth of >85 nm permits interrogation of many-grating arrays, and the demodulation technique permits fast sensing of large strains. 相似文献
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The 11B NMR spectra of borate glasses can be accurately computer-simulated using a simple model for the electric field gradient at a boron site in the BO3 and BO4 structural units, assuming these structural units are relatively undistorted. Deviations from the average OBO bond angle in these two sites are determined from the simulations to be less than ± 2° in borate glasses. There is no evidence for increasing distortion in the fundamental structural units with increasing metal oxide content. 相似文献
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The magnetization of amorphous antiferromagnetic manganese phosphate glass has been studied as a function of manganese concentration, temperature, and magnetic field. The experimental results are interpreted using a two spin model of amorphous antiferromagnetism where the probability of a given exchange interaction is calculated using crystalline Mn2P2O7 as a structural model. 相似文献
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A long-cavity, passively mode-locked erbium fiber laser operated in the square-pulse regime is demonstrated as a useful light source for interrogating fiber Bragg grating arrays. Output pulses with 4-W peak-power, 10-ns pulse widths, and bandwidths greater than 60nm were used successfully to interrogate 2% fiber Bragg gratings. 相似文献
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The behavior of the concentration of photoinduced color centers in Ge-SiO(2) optical fibers was compared with that of the index modulation associated with fiber Bragg gratings (FBG's) written in the same fibers. We find that the fluence dependence of the photoinduced Ge E? center, its thermal annealing behavior, and its reaction with H(2) are similar to that of the index modulation generated in both H(2)-loaded and unloaded Ge-SiO(2) fibers. The much higher photosensitivity of H(2)-loaded Ge-SiO(2) fibers is attributed to the much higher formation efficiency of Ge E? centers, with an additional contribution from GeH. A diamagnetic structure, possibly densification, is also found to contribute to the index modulation of FBG's. 相似文献