Design and fabrication of electro-optic polymer modulators and switches

Electro-optic (EO) polymers are interesting materials for realising active functions in integrated optics devices, since they can have relatively high EO coefficients and they can be easily combined or integrated with several (passive) materials. EO interaction can be exploited for obtaining modulation or switching in polymer-based devices using several principles (e.g. Mach-Zehnder, Digital Optical Switch or tuned coupling to surface plasmons), which have been investigated and tested using a number of different materials. We compare these principles in view of several aspects of practical importance: realistic values of EO coefficients and wavelength-dependent attenuation, optical, electrical and chemical compatibility of substrate, guiding and cladding layers, channel definition by etching (inverted) ridge waveguides or by photo-bleaching, local and global poling methods, polarisation-dependence, and the design of efficient high-bandwidth travelling wave electrodes. In most of the investigated devices, we employ a waveguiding structure based on silicon and its oxynitrides, exploiting the fact that the refractive index of silicon oxynitride can be accurately adjusted over a wide range by adjusting its composition. We will discuss the practical difficulties encountered and show the obtained results with phase- and intensity modulators and switches. (C) 1999 Elsevier Science B.V. All rights reserved.