Patent ID: 7037739

Claim:
A method for fabricating an epilayer structure for achieving the optical confinement in the vertical direction of an InGaAsP/InP waveguide phase modulator, characterized by comprising the steps of: forming a first cladding layer of N-InP on an N + -InP substrate; forming a first waveguide layer of N-InGaAsP and a second waveguide layer of P-InGaAsP in sequence on said first cladding layer; forming a second cladding layer of P-InP and a third cladding layer of P-InP in sequence on said second waveguide layer; forming an electrode layer of p + -InGaAs on said third cladding layer; and characterized in that said first and second waveguide layers are constituted of p-n homogeneous junctions for taking advantage of electric field effect and free-carrier effect.