Silicon integrated electro-optic modulators with ultra-low energy consumption

Abstract

The ambition to create photonic devices in silicon originates from the overwhelming success of complementary metal-oxide-semiconductor (CMOS) technology. In particular, high speed silicon modulators are one of the most important applications of silicon photonics to optical communication networks, where ever increasing demand for optical bandwidth and data transmission capacity is witnessed. The commercially available optical modulators nowadays, however, are mostly based on III-V compound semiconductor materials that involve CMOS incompatible processes. As a result, the low cost efficiency of the device-making process imposes obstacles for mass production in terms of integration. The main scope of this work is to design silicon based high speed optical modulators with ultra-low energy consumption. Firstly, various photonic resonance and slow light media were designed to miniaturize device footprint via an enhanced nonlinear interaction between optical resonance mode and EO active region. And a high speed of 238 GHz was theoretically predicted with an ultra-low energy consumption of 26.6 fJ/bit in a compact hybrid lattice resonator based silicon modulator. Secondly, a polymer MZI based phase shifter was studied which incorporates multiple nonlinear effects (free carrier effect and Pockels effect) for an increased EO overlapped volume. The device speed was significantly improved from previous studies by employing low aspect ratio slot waveguide geometry. A record high 3-dB bandwidth of 269 GHz was demonstrated numerically with low energy consumption of 5.83 pJ/bit. Last but not least, the hybrid lattice resonator based modulator was fabricated and measured both optically and electrically, where high level agreement was found between experimental and theoretical results.