If a rutile prism (np = 2.50) is used as an input coupler to the same waveguide as in Problem 7.1, what angle should the incident light beam make with the waveguide surface to efficiently couple into...

If a rutile prism (np = 2.50) is used as an input coupler to the same waveguide

as in Problem 7.1, what angle should the incident light beam make with the

waveguide surface to efficiently couple into the lowest order mode? Assume

the input face of the prism makes an angle of 60◦ with the waveguide surface.