Effect of fluoro-polycarbonates containing aliphatic/aromatic segments on the characteristics of thermo-optic waveguide devices

Abstract

Fluorinated polycarbonates containing dodecyl groups (AF-Ali-PC EPs), biphenyl groups (AF-Ar-PC EPs), and cross-linkable epoxy groups were synthesized to investigate the effects of the flexibility of monomers on the properties of thermo-optic waveguide devices. Transparent polymer films were prepared via photocuring of a solution (FPRs) containing AF-Ali-PC EPs or AF-Ar-PC EPs, a photo initiator, and cyclopentanone. The optical films have low surface energies and roughnesses, high thermal stabilities, and tunable refractive indices. Straight optical waveguide and MZI thermo-optic waveguide switch arrays were fabricated using Ali-PR 1 and Ar-PR 1. The propagation losses of the channel waveguides, measured by the cutback method, were 0.21 dB cm⁻¹ and 0.19 dB cm⁻¹ at the monitoring light of 1550 nm for the Ali-PR 1 and Ar-PR 1, respectively. The rise and fall times of the thermo-optic switch upon application of a 200 Hz square-wave voltage were 1.822 ms and 1.364 ms, respectively, for Ali-PRs and 2.994 ms and 2.301 ms, respectively, for Ar-PRs at the square-wave voltage of 110 Hz. The insertion loss and extinction ratio were measured to be 9.2 dB and 12.0 dB for the aliphatic segment-containing photoresists and 8.9 dB and 12.3 dB for the aromatic segment-containing photoresists, respectively. The applied electric powers were 15.0 mW and 20.0 mW, which were also the switching powers. In contrast with our previous work, fluoro-polycarbonates containing aliphatic segments were more suitable for optical waveguide devices than those containing aromatic segments.