Why are GaAs, GaAlAs and GaInAsP particularly useful materials for the fabrication of optical integrated circuits? We wish to fabricate a planar waveguide in GaAs for light of wavelength λ0 = 1.1μm...

Why are GaAs, GaAlAs and GaInAsP particularly useful materials for the fabrication of optical integrated circuits?

We wish to fabricate a planar waveguide in GaAs for light of wavelength λ0

= 1.1μm that will operate in the single (fundamental) mode. If we assume a

planar waveguide like that of Fig. 2.1 with the condition n2 − n1 >> n2 −

n3, what range of values can n2 − n3 have if n2 = 3.4 and the thickness of the

waveguiding layer t = 3μm?