(a) Sketch the index of refraction profile in a strip-loaded waveguide, indicating the relative magnitudes of the index in different regions. (b) III-V semiconductor waveguide research has progressed...

(a) Sketch the index of refraction profile in a strip-loaded waveguide, indicating the relative magnitudes of the index in different regions.

(b) III-V semiconductor waveguide research has progressed to different materials in the order shown in the list below. What reason (i.e., advantage) motivated each step in this progression?

LPE GaAs waveguides on GaAs substrates

LPE Ga(1−x)AlxAs waveguides on GaAs substrates

LPE Ga(1−x)InxAs waveguides on GaAs substrates

MBE Ga(1−x)InxAsyP(1−y) waveguides on GaAs substrates

(LPE - Liquid phase epitaxial; MBE - Molecular beam epitaxial)