Sub-Micron Bondline-Shape Control in Automated Assembly of Photonic Devices

Low-cost and scalable interfacing of optical fibers to photonic waveguides remains a significant challenge for singlemode photonic devices. We have recently proposed a compliant polymer interface connecting optical fibers to nanophotonic waveguides. It involves assembling arrays of polymer waveguides defined on a flexible polymer ribbon to nanophotonic chips. For best performance, the adhesive bondline between the ribbon and the chip must be controlled at the submicron level over the waveguide interface area with a controlled bondline increase near the chip edge. Such bondline shape and control cannot be achieved with standard techniques. In this paper, we address manufacturing compatible solutions to sub-micron bondline-shape control in automated assembly of flexible devices to rigid chips. We introduce a pneumatic chip support for bondline uniformity and employ a patterned vacuum pick tip to adjust the bondline locally to match it to a desired shape. We demonstrate a bondline control of <;0.5 um over a critical interface area of ~1 mm
²
. The approach presented here applies to sub-micron bondline-shape control of any flexible-to-rigid device assembly.