Coupled Waveguide Apparatus and Structures Therefor

摘要

Planar waveguide apparatus provides a waveguide at least partially overlying a passive buried rib waveguide for coupling optical radiation there between. The overlying waveguide has at least one tapered section, 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. The passive buried rib may have one or more unguided sections below electrically driven regions of the active waveguide to avoid parasitic modes and/or may 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.