Here are the solutions to the exercises: 1) For a GI fiber with parabolic profile, Vmax = 2.405 for single mode operation. Using the given: n1 = 1.5, Δ = 1%, λ = 1.3 μm Vmax = (2π/λ) * a * (n1^2 - n2^2)^1/2 = 2.405 Solving for a, the maximum core diameter is 5.2 μm. 2) Given: n1 = 1.54, n2 = 1.5, a = 25 μm, λ = 1300 nm NA = (n1^2 - n2^2)^1/