We wish to fabricate a planar waveguide for light of wavelength λ0 = 1.15μm that will operate in the single (fundamental) mode. If we use the protonbombardment, carrier-concentration-reduction method...

We wish to fabricate a planar waveguide for light of wavelength λ0 = 1.15μm

that will operate in the single (fundamental) mode. If we use the protonbombardment, carrier-concentration-reduction method to form a 3μm thick

waveguide in GaAs, what are the minimum and maximum allowable carrier

concentrations in the substrate? (Calculate for the two cases of p-type or ntype substrate material if that will result in different answers.)