Design of a polymer‐based phase modulator: validation of the various processes

This work is devoted to the development of technology processes with the aim of realizing a phase modulator based on organic materials. At first, a semiconductor technology is adapted to polymers to elaborate waveguides, and to realize the stacking of layers of passive and active polymers compatible with processes on a silicon substrate. By using the reactive ion‐beam etching process, we obtained waveguides with good vertical walls and propagation losses of around 0.5 dB cm −1 . For realization of the ‘whole‐polymer’ phase modulator, as a guiding layer we used the fluorinated polyimide, 6FDA/MPDA (Figure 1), mixed with a colorant, Disperse Red One (DR1); this layer is sandwiched between two organic layers with lower indices. The lower cladding layer was realized with the 6FDA/MPDA polyimide, and the upper cladding layer with poly(methyl methacrylate) (PMMA) deposited on a thin anhydride‐(6 FDA) and diamine‐(ODA) based polyimide layer obtained by vapor deposition polymerization (VDP): this layer leads to a good adherence between the active layers, while the PMMA layer can also be covered with 6FDA/ODA which then acts as a protective layer. With an infrared camera, we have shown propagation of the guided wave in a configuration‐phase modulator, and thus validated a whole technological process. Copyright © 2004 Society of Chemical Industry1. Molecular structure of the 6FDA/MPDA monomer.