A planar asymmetric waveguide is fabricated by depositing a 2 μm thick layer of Ta2O5 (n = 2.09) on to a quartz substrate (n = 1.05). (a) How many modes can this waveguide support for light of 6328 A...

A planar asymmetric waveguide is fabricated by depositing a 2 μm thick layer

of Ta2O5 (n = 2.09) on to a quartz substrate (n = 1.05).

(a) How many modes can this waveguide support for light of 6328 A (vacuum ˚

wavelength)?

(b) If a 20 (μm layer of quartz (n = 1.05) is deposited on top of the Ta2O5

waveguide, how many modes can it support for light of 6328 A (vacuum ˚

wavelength)?