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.)
References in periodicals archive ?
Proximion Fiber Systems AB is a world-class provider of optical modules and sub-systems based on Fiber Bragg Grating (FBG) technology.
Departure from linearity of fibre Bragg grating temperature coefficients.
Also, because the Bragg grating system operates by sensing the wavelength of the light reflected back from the grating, it can be more reliable and repeatable than other types of fiber-optic strain gauges that use other measurement methods such as interferometry.
Aston is a world centre of excellence on this type of technology, and particularly Fibre Bragg Gratings, and we want to be within walking distance of it.
Customized multiple wavelength reflectors can be generated by writing multiple superimposed fiber Bragg grating (FBG) reflectors into optical fiber using ultraviolet light.
We found that the state of fiber Bragg grating metrology needs improvement in most areas.
10W fiber laser pump module with 105A[micro]m fiber core diameter that operates at injection currents up to 12A; -- 1060nm seed laser module with short distance fiber Bragg grating to control spectral properties for pulsed fiber lasers; -- VHB (Very High Brightness) bar for direct systems -- launched at LASER 2007 and now being shipped in volume -- which has a power output of 80W -- up to four times the brightness of a typical 10mm bar -- and measures only 3.
While this UV photosensitivity has a detrimental effect on photolithography optics, it is very useful in fabricating integrated optic and fiber Bragg grating devices.
Tunable filters are a key building block for reconfigurable optical network elements, and are also experiencing strong demand from fiber bragg grating based optical sensing, and test and measurement applications," said Dale Flanders, President and CEO of Axsun "These tunable components are a logical extension of Axsun's dynamic optical module products.
Low-Cost, Small Footprint Solution Uses Fiber Bragg Grating to Eliminate Need for Expensive Dispersion Management in Single-Channel Deployments