Integration of polymeric micro-optical elements with planar waveguiding circuits

We report on an advanced polymer technology that enables the low-cost monolithic integration of micro-optical elements with planar waveguiding circuitry. We have developed high-performance organic polymeric materials in which both microoptical and waveguiding structures can be formed with controlled geometries. These materials are formed from highly-crosslinked acrylate monomers with specific linkages that determine properties such as flexibility, toughness, contrast, loss, and stability against yellowing. Waveguides with microns to tens of microns dimensions as well as micro-optical structures that are up to several hundred microns in thickness are printed photolithographically, with the liquid monomer mixture polymerizing upon illumination in the UW via either mask exposure or laser direct-writing. Precise control of the photochemical reaction dynamics results in high resolution in the complete thickness range. A variety of rigid and flexible substrates can be utilized, including glass, quartz, silicon, glass-filled epoxy printed circuit board substrate, and flexible polyimide film. We discuss the production of various novel micro-optical elements that we routinely integrate with waveguiding circuits. These elements include fiber grippers for waveguide pigtailing, prisms for coupling of light from VCSEL's into waveguides and from guides into photodetector chips, and pedestals for passive alignment of fiber ribbons or waveguide-array strips to waveguides.