Capitolul 04
description
Transcript of Capitolul 04
-
Chapter 4: Optical fibers and their parametersGraphic representation of three different types of how the refractive index change in the core of an optical fiber.
-
ModesGraph of the Bessel function.LP01 mode - the fundamental mode and cut-off
-
Numerical apertureThe acceptance cone of a fiber.
-
Group refractive index Refractive index profile for a primary coated fiber including the refractive index for the acrylate. Diagram shows the refractive index and group refractive index versus wavelenght used.
-
DispersionIntermodal dispersion Because the different modes follow different paths through the fiber, a light pulse is broadened in proportion to the length of the fiber.
-
Intramodal dispersion or chromatic dispersionThe chromatic dispersion is the sum of material- and waveguide dispersion.
-
Intramodal dispersion or chromatic dispersion Pulse broadening through dispersion. In single-mode fiber, intramodal and PMD dispersion occurs; in multi-mode fiber, modal dispersion causes the greatest amount of pulse broadening.
-
Polarization mode dispersion, PMDPulse broadening through polarization mode dispersion, PMD.
-
Nonlinear effects Because of the three evenly spaced wavelengths (channels) 1, 2 and 3 in this example, some of the newly generated signals occur at the original wavelengths.
-
Multimode fiber with rectangular index profileEnergy path in a step index, multimode fiber. Note that the angle (90 - ) < .
-
Multimode fiber with graded index profileRay path in a graded index multimode fiber.
-
Standard single-mode fiber with rectangular indexprofileEnergy path in an ideal single-mode fiber.
-
Chromatic dispersion in a standard single-mode fiber for the interval 1150 1600 nm.
-
Dispersion shifted fibersStandard dispersion shifted fiberChromatic dispersion for a dispersion shifted fiber and the refractive index profile.
-
Non-zero dispersion shifted fiber Graph showing the different types of non-zero dispersion fibers compared with a dispersion shifted fiber (red), included is also the refractive index profile.
-
Graph showing the chromatic dispersion in a non-zero dispersion shifted fiber and a dispersion shifted fiber. New techniques have opened two new windows, (4 and 5) for WDM. Window 3 is traditionally used for DWDM.
-
Fiber with a continuous usable bandspectrum from 1285 nm to 1625 (1700) nm.Attenuation versus wavelength for the fiber with reduced water peak. The fiber may be used continuously for 12851625 nm.
-
Dispersion-compensating fiberThe dispersion compensating modules can be used at the beginning, in the middle or at the end of a transmission link. They can preferable be combined with en EDFA.
-
The evolution of the optical fiber.