Fiber Bragg Grating
FBG

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Fiber Bragg Grating (FBG) ？

A Fiber Bragg Grating(FBG) , which has periodical perturbation of the refractive in the fiber core, function as a wavelength, selective optical fiber.
The Fiber Bragg Grating is formed directly on the fiber core and is easy to integrate into fiber opticsystem.
IT is known to reflect only the light of a specific wavelength.
When strain (extension on constraction) builds up on the optical fiber, the wavelength of the reflecter light changes.
By measuring the wavelength of the reflected light, it ispossible to determine the strain applied to the fiber at high accuracy.
Now FBG thermometer sensor, FBG pressure sensor, and other FBG sensor are launched.
LOGOS is developing other FBG sensor which is requested by austomers. Please contact us freely.

Theory of Fiber Bragg Grating

Grradiate ultraviolet rays (wavelength 250nm) to the electro fiber core which is loading with hydrogen, due-to changing optica inductive, refractive index in the fiber core also is changed, and this perturbation remain even after ultraviolet rays lighting off.
Perturbation of the refractive index in the fiber core is in proportion to depe germanium
An FBG is a grating in which the refractive index of the core of an optical fiber is changed cyclically at a certain interval.
A Fiber Bragg Grating, which has periodical perturbation of the refractive index, is the same as dielectic multiple membrance.
However FBG is known that wavelength is longer, and refractive index is smaller than dielectric multiple membrance.

Periodical perturbation of grating : Λ
Refractive index in the fiber core : n
Following the light of specific wavelenght reflects.

λB = 2nΛ

● Fiber Bragg Grating (FBG)