Hybrid polymer/sol–gel waveguide modulators with exceptionally large electro–optic coefficients

Abstract

Electro–optic (EO) modulators are typically made from inorganic materials such as LiNbO3, but replacing them with organic EO materials, that is, ones with optical properties that change in response to an electric field, could be a promising alternative because they offer large bandwidth, ease of processing and relatively low cost. Here we incorporate a doped, crosslinked organic EO polymer into hybrid polymer/sol–gel waveguide modulator devices with exceptional performance. The half-wave voltages of the resulting Mach–Zehnder (MZ) and phase modulators at 1550 nm are 1 V and 2.5 V, respectively. The unique properties of the sol–gel cladding materials used in the hybrid structure result in a 100% device poling efficiency, leading to respective in-device EO coefficients of 138 pm V–1 and 170 pm V–1 in the MZ and phase modulators. These results are the first to show in-device EO coefficients that are five to six times larger than those of the benchmark inorganic material.