Optical Fiber Communications 4th Edition by Gerd Keiser

Exercise 16

Draw a design curve of the fractional refractive-index difference versus the core radius a for a silica-core ( n 1 = 1.458), single- mode fiber to operate at 1300 nm. Suppose the fiber we select from this curve has a 5- m core radius. Is this fiber still single-mode at 820 nm Which modes exist in the fiber at 820 nm