%0 Journal Article
%T Ultrabroadband Electro-Optic Modulator Based on Hybrid Silicon-Polymer Dual Vertical Slot Waveguide
%A Shouyuan Shi
%A Dennis W. Prather
%J Advances in OptoElectronics
%D 2011
%I Hindawi Publishing Corporation
%R 10.1155/2011/714895
%X We present a novel hybrid silicon-polymer dual slot waveguide for high speed and ultra-low driving voltage electro-optic (EO) modulation. The proposed design utilizes the unique properties of ferroelectric materials such as LiNbO3 to achieve dual RF and optical modes within a low index nanoslot. The tight mode concentration and overlap in the slot allow the infiltrated organic EO polymers to experience enhanced nonlinear interaction with the applied electric field. Half-wavelength voltage-length product and electro-optic response are rigorously simulated to characterize the proposed design, which reveals ultrabroadband operation, up to 250£¿GHz, and subvolt driving voltage for a 1£¿cm long modulator. 1. Introduction Low driving voltage and high-speed electro-optic (EO) modulators are of great interest due to their wide variety of applications including broadband communication, RF photonic links, millimeter wave imaging, and phased-array radars. In order to attain optical modulation at low driving voltages, a strong mode concentration and a tight mode overlap between optical and radio-frequency (RF) modes in the nonlinear EO material are required. Typically, to maintain a single mode operation in optical domain, the optical mode size is on an order of wavelength, that is, 2£¿um at telecommunication region. As a result, to match with the optical mode, the RF guiding structure essentially has to reduce a factor of three orders of magnitude. Conventional traveling wave EO modulators are usually driven by RF transmission lines, such as coplanar waveguides (CPWs) and microstrip lines. These electrode designs provide not only high speed operation but also a strong overlap between optical and RF modes. While the device operates at very high frequency, that is, over 20£¿GHz, the RF wave propagation attenuation attributed from both conduction loss and dielectric loss becomes the key issue that prevents the device from operating over a wide bandwidth. Physically, a small mode size provides a strong RF field concentration, or a small mode volume, however, leads to a significant increase in propagation loss. As a result, an optimal design of RF electrode design including signal electrode and gap between signal and ground is required to minimize the overall RF propagation loss. To date, many high speed traveling wave EO modulators have been designed, fabricated, and characterized, leading to operation at speeds as high as 140£¿GHz. Most of these modulators were developed using crystalline EO materials, such as LiNbO3 [1¨C5] and GaAs [6, 7]. Recently, tremendous efforts
%U http://www.hindawi.com/journals/aoe/2011/714895/