Advanced polymer systems for optoelectronic integrated circuit applications

Abstract

An advanced versatile low-cost polymeric waveguide technology is proposed for optoelectronic integrated circuit applications. We have developed high-performance organic polymeric materials that can be readily made into both multimode and single-mode optical waveguide structures of controlled numerical aperture (NA) and geometry. These materials are formed from highly crosslinked acrylate monomers with specific linkages that determine properties such as flexibility, toughness, loss, and stability against yellowing and humidity. These monomers are intermiscible, providing for precise adjustment of the refractive index from 1.30 to 1.60. Waveguides are formed photolithographically, with the liquid monomer mixture polymerizing upon illumination in the UV via either mask exposure or laser direct-writing. A wide range of rigid and flexible substrates can be used, including glass, quartz, oxidized silicon, glass-filled epoxy printed circuit board substrate, and flexible polyimide film. We discuss the use of these materials on chips and on multi-chip modules (MCMs), specifically in transceivers where we adaptively produced waveguides on vertical-cavity surface-emitting lasers (VCSELs) embedded in transmitter MCMs and on high- speed photodetector chips in receiver MCMs. Light coupling from and to chips is achieved by cutting 45 degree mirrors using excimer laser ablation. The fabrication of our polymeric structures directly on the modules provides for stability, ruggedness, and hermeticity in packaging.