OPTICAL WAVEGUIDE STRUCTURE INCLUDING CASCADED ARRAYS OF TAPERED WAVEGUIDES

摘要

A waveguide structure comprising a plurality of cascaded arrays of tapered waveguides which are operably coupled to one another. The tapered waveguides are each characteristically arranged so as to taper from a wide end to a narrow end along a direction light propagation through the tapered waveguides. This cascaded arrangement increases the pickup of primarily on-axis light (i.e., input light that is substantially parallel to axes of the tapered waveguides) and the rejection of off-axis light (i.e., input light that is outside of a certain angular range relative to the axes of the tapered waveguides). In order to prevent recapture of the rejected light, one or more solutions are provided according to the present invention. The waveguide structure may be curved out of the plane containing the cascaded tapered waveguides, or straight waveguides may be provided between the tapered waveguides so as to increase the distance therebetween. In addition, secondary tapered waveguides may be provided between adjacent cascaded tapered waveguides so as to redirect rejected light in a manner that decreases the likelihood of recapture in the light propagating path.