Coupled planar waveguides for optoelectronic devices

摘要

The disclosed arrangement of planar waveguides provides a waveguide 100 at least partially overlying a passive buried rib waveguide 140 and arranged to couple optical radiation therebetween. The overlying waveguide 100 has at least one tapered section 200, the width of the taper determining the degree of coupling between the waveguides at points along the tapered section. The overlying waveguide may have an active core region 205. The passive buried rib 140 may have one or more unguided sections below electrically driven regions of the active waveguide to avoid parasitic modes. It may also provide a grating for use as a filter or feedback. Variations include a branched passive waveguide for coupling to two or more overlying waveguides and two or more aligned and active overlying waveguides coupling to one passive waveguide, there being a break in a shared core region of the active waveguides to provide electrical isolation between them. In general, the buried rib design can avoid problems with epitaxial growth onto etched quaternary surfaces and with very exacting accuracy requirements in fabrication.