Polymer tapered waveguides and flip-chip solder bonding as compatible technologies for efficient OEIC coupling

Abstract

Optoelectronic technologies and devices have developed at a rapid rate, resulting in a large array of materials systems and structures that may be integrated into optoelectronic modules and subsystems. However, because these devices are made of a variety of materials systems, there is a fundamental mismatch between their optical modes. This mismatch affects coupling efficiency and sensitivity to tolerances. The coupling efficiency between laser diode arrays or OEIC components and single-mode fiber ribbons drops rapidly with increasing misalignment tolerance. There are trade-offs between the allowed minimum coupled power and the cost of establishing the required alignment. We are using a polymeric waveguide film that contains optical structures to transform optical mode patterns between components made from dissimilar materials systems. We demonstrate how tapered polymer waveguides may be used to match the laser mode to the fiber mode, resulting in a module with decreased alignment requirements for a given coupling efficiency Waveguides which simultaneously taper the mode both laterally and vertically have been designed. Waveguides with tapered mode profiles have been constructed using photobleaching of a guest/host dye/polymer system. Amoco 4212 polyimide doped with DCM dye was chosen as the waveguide material due to its good thermal stability and its simple processing. We present numerical results showing the variation of coupling efficiency into tapered waveguides with component misalignment. The alignment between components is established by self-aligned flip-chip solder bonding.