Polarization-Independent Electro-Optic Polymer Devices with Twisted Optic-Axis Waveguide Polarization Converters

Abstract

Electro-optic waveguide devices are essential components for the high-speed photonic signal processings and broadband optical communications. In the lightwave signal transmission, the polarization state of the light is not maintained when a standard single-mode fibers are used. Hence, polarization independent EO devices are preferred to reduce the system complexity caused by an adaptive polarization controlling circuit. In lithium niobate substrates, there have been various investigations for the polarization-independent switches such as mode-evolution type digital switches [1], directional coupler switches with coincident coupling length for TE and TM modes [2], Mach-Zehnder (MZ) switches on x-cut, z-propagating orientation providing degenerated TE and TM modes [3], The switching voltages of these devices are 17 ~ 60 V. In this work, we propose a polarization-independent polymer waveguide modulator [4] which can be realized by integrating a polymeric polarization converters [5] in the middle of the MZ modulator. The optic-axis of the polarization converting waveguide is twisted 90 degree by poling it with specially designed electrodes.