The fibre has a core refractive index of 1.47.
The radius a and the relative refractive index difference ? are to be selected to make this a single mode fibre.Sketch a design characteristic of refractive index difference ? versus core radius for the fibre representing the conditions for single mode propagation at a wavelength of 1.3 Um.Determine whether this fibre remains single-mode at a transmission wavelength of 0.85 Um when its core radius is 4.5 Um.