Single-mode optical waveguides and phase modulators in the InP material system

The characteristics of several different single-mode optical waveguides in the InP material system are discussed. Slab-coupled rib waveguides in GaInAsP (lambda_{gap} approx 1 mum) epitaxial layers grown on InP have shown propagation losses as low as 1.7 cm^-1at 1.3 μm and 2.7 cm^-1at 1.15 μm. Oxide-confined InP rib guides fabricated using a lateral overgrowth technique have losses of about 1.5 cm^-1at 1.15 μm. Three-guide couplers have been made by fabricating three parallel oxide-confined guides in close proximity. InP p+-n-n+ guides capable of modulating TE-polarized radiation have been fabricated using epitaxial techniques and Be-ion implantation. By measuring the phase difference between the TE-like and TM-like modes as a function of applied voltage, an estimate of the r41electrooptic coefficient in InP at 1.3 μm that is in good agreement with a previously reported value was obtained. Guides of this type should find use as the active components in InP switches and interferometers.