Polymer in-line fiber modulators for broadband radio-frequency optical links

Abstract

We present a polymer in-line fiber modulator with a rugged and low-loss interface to single-mode fibers that can be engineered to have a bias point that yields linear modulation over a large dynamic range. Two classes of large-bandwidth modulators, each of which benefits from different properties provided by polymers, are demonstrated. A lumped capacitor modulator, which uses a decal deposition technique, and a traveling-wave modulator, which takes advantage of polymer conformal coating and reactive ion etching to accurately trim the thickness of the polymer waveguide, are presented. Because the in-line fiber modulator configuration requires moderate loss to achieve a large dynamic range, an operational wavelength closer to the absorption peak of an electro-optic polymer can be used to exploit the resonant enhancement of electro-optic coefficients.