(2) Consider group velocity dispersion in a medium described by the Sellmeier equation: (a) Derive expressions for the group index N and the group velocity dispersion coefficient D . (b) Plot the wavelength dependence of n, N and D, for fused silica in the region between0.25 and 3.5 µm, and for GaAs in the region between 1.5 and 10.5 µm. Compare and contrast their dispersive properties. Use the parameters provided in Table 2.1 (Module 2,slide 27 of the course notes; i.e., Saleh & Teich, 2nd ed., p.180).

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