Dispersion profile

In addition to the influence of the radial velocity profile, dispersion caused by molecular diffusion, which takes place in both axial and radial directions, may also play a certain role. The diffusion in radial direction tends to counteract the spreading effect of the velocity profile, while axial molecular diffusion increases the dispersion (details in Section 4.10.6.3). Instead of the simple differential mass balance of a plug flow reactor [Eq. (4.10.23)], the differential equation of a steady-state nonplug flow tubular reactor is ... 

A high bandwidth can typically be achieved when the profile exponentg is approximately equal to 2.0. However, the refractive indices of materials generally depend on the wavelength, which induces profile dispersion. 

The profile dispersion p caused by the wavelength dependence of the refractive index [7] is given by... 

On the other hand, the value, which represents the highest bandwidth, shifted to around 2.4 because of profile dispersion, as discussed above. The dopant used in all the GI POFs shown in Figure 3.2 was diphenyl sulfide, and all the GI POFs had NAs of 0.20. This result indicates that the bandwidth characteristics are strongly influenced by the profile dispersion even if the refractive index profile deviates greatly from the ideal one. 

MarcatiU, E. (1977) Modal dispersion in optical fibers with arbitrary numerical aperture and profile dispersion. Bell Syst Tech. /., 56, 49-63. 

Measurement of Other 0[4ical Properties. Measurement of other optical properties such as strain-, electro-, magneto-, and acoustooptical effects involve specialized techniques beyond the scope of this chapter. The same is true for measurements of transmittance, refractive index profile, dispersion, and other important properties of optical communications fiber. Birefringence and strain-optical measurements will, however, be discussed in Chap. 6, in relationship to annealing and strengthening of glass. 

The slight change in value of the optimum profile exponent from to q due to profile dispersion is given approximately by 5q = — 2p, assuming the weak-guidance expressions in Eqs. (3-8) and (3-20). Althou dq, is small, it nevertheless has a dramatic effect on pulse dispersion. We calculate the ray dispersion t = —... 

Gambling, W. A., Matsumura, H. and Ragdale, C. M. (1979) Mode dispersion, material dispersion and profile dispersion in graded-index, single-mode fibers. Microwaves, Opt. Acoust. 3, 239-46. 

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