Highly sensitive dynamic strain measurements by locking lasers to fiber Bragg gratings

Lissak, Boaz; Arie, Ady; Tur, Moshe

doi:10.1364/ol.23.001930

Cited by 112 publications

(54 citation statements)

References 8 publications

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“…Our model shows, as expected on physical grounds, that in the vicinity of this wavelength the group velocity of light is also reduced, although not as much as at the wavelengths reported in this paper. Although the concept of slow light was not mentioned in [18], it is our opinion that this reference did utilize slow light, and that the low MDS they report is likely due mostly to slow light. Also, in [19], strain detection was effected by probing a -shifted FBG in the vicinity of the narrow high-transmission peak that exists in the middle of its bandgap.…”

Section: B Measurements Of Strain Sensitivitymentioning

confidence: 86%

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Sensing With Slow Light in Fiber Bragg Gratings

et al. 2012

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On the edge of the bandgap in a fiber Bragg grating (FBG) narrow peaks of high transmission exist at frequencies where light interferes constructively in the forward direction. In the vicinity of these transmission peaks, light reflects back and forth numerous times across the periodic structure and experiences a large group delay. Since the sensitivity of a phase sensor to most external perturbations is proportional to the reciprocal of group velocity, in these slow-light regions the sensitivity of an FBG is expected to be significantly enhanced over traditional FBG sensors operated around the Bragg wavelength. In this paper, we describe means of producing and operating FBGs that support structural slow light with a group index that can be in principle as high as several thousand. We present simulations elucidating how to select the FBG parameters, in particular index modulation, length, and apodization, to generate such low group velocities, and quantify the very large improvement in strain and temperature sensitivities resulting from these new slow-light configurations. As a proof of concept, we report an FBG with a group index of 127, or a group velocity of 2 360 km s. This is by far the lowest group velocity reported to date in an FBG. Used as a strain sensor, this slow-light FBG is shown to be able to detect a strain as small as 880 f Hz, the lowest value reported for a passive FBG sensor.

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Section: B Measurements Of Strain Sensitivitymentioning

confidence: 86%

“…On the other hand, it is interesting to note that two other published approaches have led to an even better MDS than the conventional result of [17]. One is an FBG that was probed in reflection not at as is customary but at a wavelength on the falling edge of the bandgap [18]. This scheme achieved an MDS of 45 .…”

Section: B Measurements Of Strain Sensitivitymentioning

confidence: 98%

Sensing With Slow Light in Fiber Bragg Gratings

et al. 2012

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“…For the first two cases, several techniques based on frequency-locked laser have been used to improve the strain measurement resolution [1,2]. A dynamic and quasi-static strain resolution of pε has been demonstrated in the last decade [3,4].…”

Section: Introductionmentioning

confidence: 99%

Distributed feedback fiber laser for sub-nanostrain-resolution static strain measurement by use of swept beat-frequency demodulation

Huang

Zhang

2015

SPIE Proceedings

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Fiber laser has the advantages of ultra-narrow linewidth, low phase and intensity noise, which is beneficial for ultrahigh-resolution strain sensing. This paper presents a novel demodulation technique for sub-nanostrain-resolution static strain measurement based on two distributed feedback fiber lasers (DFB FLs). A commercial PZT-tunable laser is used to interrogate the DFB FLs and get the periodic frequency-difference characteristics (two linear chrip signals) by swept beat-frequency principle. Two polarization controllers are used for adjusting the polarization direction of DFB FLs. And one of the two DFB FLs is used for temperature compensation and eliminating the frequency shift influence of the commercial laser. Static strain is demodulated by calculating the difference of the direct current (DC) components of the two swept beat-frequency signals. A static-strain resolution of 0.88 nε is obtained in the laboratory test.

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“…Optical fiber sensors are attractive for this application due to the well-know advantages such as small size, low cost, immune to electromagnetic interference, linear response and ability of remote and multiplexed sensing. However, although there are several reports of dynamic FBG strain sensing realizing even better than nH sensitivity [1][2][3], up to now the application of fiber sensor in the field of static strain sensing is not so successful. One reason is that the realization of static strain sensing is much more difficult than dynamic sensing.…”

Section: Introductionmentioning

confidence: 99%

An ultra-high-resolution large-dynamic-range fiber optic static strain sensor using Pound-Drever-Hall technique

Liu

Tokunaga

et al. 2011

2011 International Quantum Electronics Conference (IQEC) and Conference on Lasers and Electro-Optics (CLEO) Pacific Rim Incorpo

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In this paper we report the realization of a fiber optic static strain sensor with ultra-high resolution and large dynamic range for the applications of geophysical research. The sensor consists of a pair of fiber Bragg grating based Fabry-Perot interferometers for strain sensing and reference, respectively. Pound-Drever-Hall technique is employed to interrogate the sensor heads, and a cross-correlation algorithm is used to figure out the strain information with high precision. Static strain resolution down to 4.5 nH was demonstrated. The dynamic range can be extended up to hundreds of PH, and the measuring period is a few tens of seconds.

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Highly sensitive dynamic strain measurements by locking lasers to fiber Bragg gratings

Cited by 112 publications

References 8 publications

Sensing With Slow Light in Fiber Bragg Gratings

Sensing With Slow Light in Fiber Bragg Gratings

Distributed feedback fiber laser for sub-nanostrain-resolution static strain measurement by use of swept beat-frequency demodulation

An ultra-high-resolution large-dynamic-range fiber optic static strain sensor using Pound-Drever-Hall technique

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