Figure 9. Blackbody fiber optic sensor.
The most widely used wavelength based sensor is the
Bragg grating sensor. Fiber Bragg gratings (FBGs) are
formed by constructing periodic changes in index of
refraction in the core of a single mode optical fiber. This
periodic change in index of refraction is normally created
by exposing the fiber core to an intense interference
pattern of UV energy. The variation in refractive index so
produced, forms an interference pattern which acts as a
grating.