Core position alignment in polymer optical waveguides fabricated using the Mosquito method

Abstract

We fabricate multimode polymer optical waveguides with circular graded-index (GI) cores which are aligned in parallel at desired positions using the Mosquito method. In the Mosquito method, three-dimensional wiring patterns can be formed with a simple process. However, the core position is likely to deviate from the designed position because of multiple fabrication factors. Hence, in this paper, the dominant parameters to influence on the core height in the cladding are investigated both theoretically and experimentally. In particular, a linear relationship between the core height and the needle-tip height is confirmed with theoretical fluid analysis. Using this relationship, we succeeded in fabricating a waveguide in which the maximum variation of the core height from the designed value is controlled to be less than 10 µm.

Multi-Channel Single-Mode Polymer Waveguide Fabricated Using the Mosquito Method

“…8 in addition to a plane 9 mm behind the needle back-side edge. We already simulated the side view cross-section using the COMSOL Multiphysics software in the same way [15], and showed that just after being dispensed, the core monomer ascends slightly in the cladding monomer and gradually descends after leaving the needle. The core monomer flow trajectory shown in Fig.…”

“…When the dispensing angle is 0°, the edge of the needle scrapes a dip into the top of the core area. After the core monomer exits the backside edge, it ascends along the edge of the needle because a lower pressure area exists just behind the needle [15]. However, the core monomer does not sufficiently ascend to fill the dip and thus, a heart-like shape remains.…”

“…In the Mosquito method, the core height needs to be precisely controlled (in the vertical direction) as well, in order to efficiently connect to other optical components such as laser/detector and SMF arrays via MT/MPO connectors. We have already reported on the core height control in a multimode waveguide [15], and found that the flow of the cladding monomer during needle scan also needed to be taken into consideration to control the core height. Therefore, controlling the core height in single-mode waveguides should be a more difficult issue, and it is essential to optimize the fabrication conditions by taking not only the positional accuracy of the automated stage but also the flow of the monomers into account.…”