Fiber Optomechanics
- Beam Splitters and Combiners
- Collimators
- Fiber Adapters
- Fiber Bragg Grating
- Fiber Optic Couplers
- Fiber Mirrors
- Fiber Optic Attenuators
- Fiber Patch Cords
- Fiber Probes
- Power Shutter and Safety Interlock
- Fiber Tunable Filters
- Fiber Optic Gyroscopes
- Transmitters and Receivers
- Ferrules
- Fiber Alignment Structures
- Fiber Fanouts
- Fiber Coils
FILTER PRODUCTS
Fiber Bragg Grating
Frequently Asked Questions
Sir William Lawrence Bragg is a physicist who proposed a diffraction law for x-rays which was later generalized for all wavelengths. His name was attributed to this law in which he explained the interference of waves reflecting at two planes separated by a short distance.
The grating period is defined as the closest distance between two identical points in a periodic structure such that the entire periodic pattern can be reconstructed with the slice that falls between those points. This separation depends on the wavelength of interest and the effective refractive index of the material and is typically on the order of hundreds of nanometers.
The most popular fiber grating structures are uniform grating, tilted grating (the pattern is angled), chirped, and superstructure.
The Bragg wavelength is the wavelength of reflected light or light that does not get transmitted by the fiber. It is proportional to twice the period of the grating period with the effective refractive index as the proportionality coefficient.
As one might imagine FBGs exhibit sensitivity to strain, which can spatially distort/alter the periodic pattern in the fiber. Strain causes a shift in the Bragg wavelength which is proportional to the amount of strain applied. Therefore measuring the shift in the transmitted wavelength one can measure the strain exerted on the fiber. The relative shift of the Bragg wavelength is directly proportional to the applied strain.
Yes, Bragg gratings exist in both single-mode and multimode fibers. The main difference between the two technologies is that multimode fibers support different many modes which have a slightly different effective refractive index. This means that different modes will have different Bragg wavelengths and different effects that must be accounted for in the design of the grating.
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