Synthesis and characterization of cross-linkable polyurethane-imide electro-optic waveguide polymer

The novel electro-optic (EO) polymers of fluorinated cross-linkable polyurethane-imides (CLPUI) were designed and synthesized by polycondensation of azo chromophore C1 and C2, diisocyanate MDI, and aromatic dianhydride 6FDA. Molecular structural characterization for the resulting polymers was achieved by 1HNMR, FT-IR, elemental analysis, and gel permeation chromatography. The polymers exhibit good film-forming properties, high glass transition temperature (Tg) in the range of 193–200 °C, and thermal stability up to 290 °C. The polymers that possess a high EO coefficient (γ33\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\gamma_{33}$$\end{document} = 48 and 56 pm/V) at 1550 nm for poled polymer thin films were measured by the simple reflection technique. Excellent temporal stability and low optical losses in the range of 1.1–1.7 dB/cm at 1550 nm were observed for these polymers. Using the synthesized side-chain electro-optic CLPUI as the active core material and of a fluorinated polyimide as cladding material, we have designed and successfully fabricated the high-performance polymer waveguide Mach–Zehnder EO modulators.