A three-layer planar waveguide structure consists of a 5μm thick waveguiding layer of GaAs with electron concentration N = 1 × 1014 cm−3, covered on top with a confining layer of Ga0.75Al0.25 As with...

A three-layer planar waveguide structure consists of a 5μm thick waveguiding

layer of GaAs with electron concentration N = 1 × 1014 cm−3, covered on

top with a confining layer of Ga0.75Al0.25 As with N = 1 × 1018 cm−3, and

on bottom with a confining layer of GaAs with N = 1 × 1018 cm−3. If this

waveguide is used to guide light of λ0 = 1.06μm, how many modes can it

support?