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

Abstract Electrooptic (EO) waveguiding polymer devices are very attractive for optical 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 polarization dependant response precludes any actual use in optical telecommunication systems. The traditional uniform poling procedure, a prerequisite processing step for electrooptic polymer based devices whereby an electric field is applied at the vicinity of the glass transition temperature, results in uniform 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 axis can, however, be imprinted onto the material, thus resulting in the possibility of balanced TE/TM polarization efficiencies. Monolithic integration of both electrode configurations within a Mach–Zehnder (MZ) modulator is shown to result in an original polarization insensitive electrooptic polymer amplitude modulator for integrated optics. Design procedures including modeling, fabrication as well as performance testing of the integrated sandwich and transverse electrode configurations device are discussed. Cladding is selected in view of ensuring both efficient poling conditions and maximal overlap of the modulation field with the active layer cross-section. Corresponding optimizations are presented for both electrode configurations.