The Rayleigh scattering coefficient for a silica SMSIfiber a

The Rayleigh scattering coefficient for a silica SMSI-fiber at a wavelength of 0.80 mu m is 0.46 km. The fiber has a refractive index of 1.6 and a numerical aperture of 0.14. When a light pulse of 60 ns duration at a wavelength of 0.80 mu m is launched into the fiber, calculate the level in dB of the back scattered light compared with the Fresnel reflection from a clean break in the fiber. It may be assumed that the fiber is surrounded by air. (Senior 13-16/829).

Solution

wavelength of 0.8

refractie index of 1.6

numerical apertu of 0.14

light pulse of 60

wavelength0.80

he rayleigh scattering coefficient for a silica sMsI fiber at a wavelength of 0.80

so, the silicon fiber wavelength 0.08

so,te level in dbof the ack scattered light compared with the fresnel reflection from a clear in the fiber.

wavelength 0.80+60

60.80

so the level of the back scattered light compared with the fresnl reflection from a cear break in the fiber is 16.86.