Optical fiber. Modify the code from the previous problem so that the waveguide consists of a dielectric with n = 2 with radius 2.0 cm, and a region of free space outside the dielectric. Terminate the simulation space outside the free space region with PEC, at a radius large enough so that evanescent fields outside the dielectric are small. Excite this fiber at one end as in the problem above, and plot snapshots of the field pattern a few wavelengths down the fiber.