Alan Freedman -- The Computer Language Company - Computer Desktop Encyclopedia
Computer Desktop Encyclopedia
Longest-Running Tech Reference on the Planet

A CDE Definition

You'll love The Computer Desktop Encyclopedia (CDE) for Tech Term of the Day (TTOD)

LOOK UP ANOTHER TERM


Bragg grating

See fiber Bragg grating.



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.)






Personal Use Only

Before/After Your Search Term
BeforeAfter
bppbrain-computer interface
BPQLbrain dump
BPRbrain-machine interface
bpsbrain mapping
BPSKbrain scanning
BPSSbrains
BQFPbranch
bracesbranch prediction
bracketbranding
bracketingbranding fiascos

Terms By Topic
Click any of the following categories for a list of fundamental terms.
Computer Words You Gotta KnowSystem design
Job categoriesUnix/Linux
Interesting stuffPersonal computers
InternetIndustrial Automation/Process Control
Communications & networkingAssociations/Standards organizations
HistoryDesktop publishing
Audio/VideoGraphics
MainframesSecurity
ProgrammingHealthcare IT
System design