Polymer based polarization insensitive amplitude modulator: conception, technology and demonstration

Electrooptic (EO) waveguiding polymer devices are very attractive for optic al communication systems by virtue of their simple and potentially low-cost fabrication procedures. Several functions such as high speed modulation or switching, have been already demonstrated. However, their so-far polarizat ion dependant response precludes any actual use in optical telecommunicatio n systems. The traditional uniform poling procedure, a prerequisite process ing step for electrooptic polymer based devices whereby an electric field i s applied at the vicinity of the glass transition temperature, results in u niform statistical polar orientation of the chromophores, and is. therefore , responsible for polarization sensitivity. By means of different coplanar or sandwich electrode configurations, any desired prerequisite modulation a xis can, however, be imprinted onto the material, thus resulting in the pos sibility of balanced TE/TM polarization efficiencies. Monolithic integratio n of both electrode configurations within a Mach-Zehnder (MZ) modulator is shown to result in an original polarization insensitive electrooptic polyme r amplitude modulator for integrated optics. Design procedures including mo deling, fabrication as well as performance testing of the integrated sandwi ch and transverse electrode configurations device are discussed. Cladding i s selected in view of ensuring both efficient poling conditions and maximal overlap of the modulation field with the active layer cross-section. Corre sponding optimizations are presented fur both electrode configurations. (C) 2000 Elsevier Science S.A. All rights reserved.