Silicon-On-Insulator-Based Photonic-Crystal Mach-Zehnder Interferometers

Si nanophotonics is anticipated to play a critical role in the future ultra-compact system integration due to the maturity of sub-micron silicon complementary metal oxide semiconductor (CMOS) technology. Photonic crystals (PhCs) provide a promising platform for developing novel optoelectronic devices with significantly reduced device size and power consumption. The active control of photonic crystal waveguides (PCWs) incorporated in Mach-Zehnder interferometers has been investigated in this paper. We designed and fabricated a PCW based silicon thermo-optic (TO) switch operating at 1.55 μm. A novel device structure was proposed to enhance the heat exchange efficiency between the source and the active PCW region, which resulted in a faster switching time (< 20μs) compared with the conventional structure. The required π phase shift between the two arms of the MZI has been successfully achieved within an 80 μm interaction distance. The maximum modulation depth of 84% was demonstrated for switching power of 78mW. For high-speed applications, a p-i-n structure based PCW electro-optical (EO) MZI modulator was proposed. The transient performance of such a device was evaluated using a two-dimensional semiconductor device simulator MEDICI. The simulated structure demonstrated a great potential to realize high-speed ultra-compact Si modulators in the GHz region.