fiber Bragg grating

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fiber Bragg grating

A short length of optical fiber that filters out a particular wavelength. Periodically spaced zones in the fiber core are altered to have different refractive indexes slightly higher than the core. This structure selectively reflects a very narrow range of wavelengths while transmitting others. Fiber Bragg gratings are used to stabilize the output of a laser and to filter out wavelengths in a WDM system.

The name comes from Bragg's Law, which is used to create the spacing of the changes. Sir William Lawrence Bragg, noted British physicist (1890-1971) discovered this in his study of x-rays and crystal structures. See diffraction grating and WDM.

A Fiber Bragg Grating
Fiber Bragg gratings such as this one from JDS Uniphase can be customized for a variety of applications covering a range of wavelength bands from 850 to 1650 nm. (Image courtesy of JDS Uniphase.)

The Gratings Reflect
In this example, the red wavelength matches the grating period and is reflected. The blue wavelength is transmitted because it does not match the grating spacings. (Illustration assistance courtesy of Jeff Hecht.)

Optical Circulators
Since the desired wavelength is reflected back by the grating, another device known as an "optical circulator" detects and switches it. (Illustration courtesy of Jeff Hecht.)
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References in periodicals archive ?
Lopez-Higuera, "Interrogation unit for fiber Bragg grating sensors that uses a slanted fiber grating," Optics Letters, vol.
Zhang, "A diaphragm-type fiber Bragg grating pressure sensor with temperature compensation," Measurement, vol.
When the Fiber Bragg Grating has been acted by stress and temperature and other external factors, due to the elastic action it will result in the transformation about the effective refractive index [n.sub.eff] and the grating period [LAMBDA], while the transformations related to these parameters will result in change in the reflection wavelength of the grating.
Han, "Estimation of dynamic structural displacements using fiber Bragg grating strain sensors," Journal of Sound and Vibration, vol.
Othman, "An Analysis of 10 Gbits/s Optical Transmission System using Fiber Bragg Grating (FBG)," IOSR Journal Of Engineering, vol.
Toyserkani, "Sensitivity alteration of fiber Bragg grating sensors with additive microscale bi-material coatings," Measurement Science and Technology, vol.
In this study, the Fabry-Perot interferometer made of fiber Bragg gratings (FBGs) was applied to the AE sensor in order to improve the convenience in handling, and the proposed sensor was used to detect artificial AE signals caused by dropping the steel ball.
Fiber Bragg gratings (FBGs) have become popular sensors for measuring temperatures at many points on large structures or distributed over a long distance.
The fiber Bragg grating FBGti_1 corresponds to the complementary code sequence [C.sub.M,O,m] of the 1D active weight TCK codes; it allows the code sequence [C.sub.M,O,m] through and filters out the complementary code sequence [C.sub.M,O,m].
One of the most interesting candidate is the fiber Bragg grating (FBG) sensor, which can provide localized measurements with high sensitivity and good linearity.
Manjunath," Design & Simulation of Optical Fiber Bragg Grating Pressure Sensor For Minimum Attenuation Criteria", Journal of Theoretical and Applied Information Technology, Vol.5,pp 515-530 (2009).