Process characterization for direct dispense fabrication of polymer optical multi-mode waveguides

Abstract

The use of optical waveguide technology in printed circuit boards offers improvement in high speed data transfer. Transitioning current material deposition techniques for waveguide fabrication from small scale laboratory environments to large scale manufacturing presents significant physical and financial challenges. To address these issues, a syringe based direct dispense tool was characterized for repeatable direct write dispensing of blanket layers of waveguide material over a range of thicknesses (25–220 µm), reducing waste material and affording the ability to utilize large substrates. This tool was also used to directly dispense discrete multimode waveguide cores requiring no UV definition or chemical development. The ability to directly dispense waveguides reduces production costs by eliminating material waste and the need for costly photo-masks. The direct dispense waveguide cores had near circular cross sections ∼50 µm in diameter, with total optical losses in the range of 0.06–0.09 dB cm–1 at 850 nm compared to <0.05 dB cm–1 losses of lithographically fabricated square waveguides. The most critical process variables for dispensing functioning polymer waveguides are identified and discussed.