Low-driving-voltage electro-optic polymer modulators for advanced photonic applications

Abstract

The rapid development of ultra-wide bandwidth fiber optical communications networks has challenged circuit designers to obtain ever-increasing link gain-bandwidth products with new electro-optic modulators. As the link bandwidth increases, high power modulator drivers become very costly and have low efficiency. To overcome the limited gain-bandwidth product, it is important to reduce the required driving voltage or the so-called halfwave voltage of current electro-optic modulators. In this paper, we report results on new polymeric electro-optic modulators with a halfwave voltage of 0.8V and a halfwave voltage-interaction length product of 2.2V-cm. The low driving voltage allows electro-optic modulators to be driven directly by high-speed logic circuits without an amplifier. The driving electronics and the system cost can be significantly reduced when these modulators are implemented. Here, low halfwave voltage modulators are based on recent developments in materials and modulator fabrication technologies. The incorporation of a new second-order nonlinear optical chromophore CLD-1 in a poly(methylmethacrylate) matrix has a demonstrated electrooptic coefficient approximately 60 pm/V at 1318 nm wavelength. Using this material system and an optical push- pull modulator design, sub-1 volt Mach Zehnder modulators and temporal stability of these modulators will be reported.