Integrated photonic retroreflectors for lateral cross-connects and interconnects

A new photonic architecture for integrated retroreflection is presented. High contact angle polymer microdroplets are dispensed in ambient filler solutions to create spheroid microdroplets, for which incident beams can be made to focus, back-reflect and retroreflect in planar topologies. Results are shown for microdroplet retroreflectors with radii ranging from 50 μm to 2 mm. It is found that a balancing of surface tensions between the filler fluid, liquid, and solid substrate can be used to modify the structure´s eccentricity and produce the required geometrical profile for lateral beam retroreflection. Such structures will be well-suited to integrated photonic topologies employing cross-connects and interconnects in planar switching/routing applications.