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Disadvantages Of Waveguide Dispersion

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2.6.2.2 Waveguide Dispersion
The effective index varies with wavelength not only due to of material dispersion, but also because varies with . In turn, it varies with wavelengths. These implicit variations of [ ] with gives rise to the second cause for chromatic dispersion, which is term waveguide dispersive [D37]. The total dispersive are combinations of the relative contributions of waveguide dispersion and material dispersion for a conventional single-mode fibers. The zero-dispersive wavelength may be shifted to a higher value by controlling the waveguide contribution [50]. It is possible to design fibers such that is shift into the vicinity of 1.55 , such fibers are referred to as dispersive-shifted fibers (DSFs) . The
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When different polarization components of an optical signal experience different indices of refractive, they propagate with different velocities, causing pulse broadening and dispersion. These effect are known as polarization mode dispersion (PMD). PMD are a basic properties of single mode fibers that affects the magnitude of the transmission rate [D191]. Time domain effects of PMD in a shorter fibers length with a pulses being launched with equal powers on the two birefringent axes, x and y, become two pulses at the output separate by the differential group delay (DGD) see Fig.(2.9)…show more content…
The variation of power within the channel causes changes in the refractive index [D305]. By changing the refractive index, the phase velocity of light changes and the optical field acc-
-umulates an extra phase shift. This effect is known as SPM since light causes a phase change on itself [DH96]. SPM refers to the selinduced phase shift experienced by an optical field during its propagation in optical fibers. The intensity-dependent nonlinear phase shift [D305] In XPM, the refractive index changes due to variations in power not only in the observed channel but also due to variation in powers of other wavelength channels leading to the pulse distortion [D305]. Changes in the refractive index and phase shifts can also be created by a second optical field which is either at a different wavelength or on a different polarization. This type of interaction is called XPM. Such optically-induced phase shifts used in several types of interferometric and dual-mode structures for optical switching [DH96].

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