Wavelength Locking and Thermally Stabilizing Microring Resonators Using Dithering Signals

Abstract—The bandwidth bottleneck looming for traditional electronic interconnects has driven the consideration of optical communications technologies as realized through the complemen-tary metal-oxide-semiconductor-compatible silicon nanophotonic platform. Within the silicon photonics platform, silicon microring resonators have received a great deal of attention for their ability to implement the critical functionalities of an on-chip optical net-work while offering superior energy-efficiency and small footprint characteristics. However, silicon microring-based structures have a large susceptibility to fabrication errors and changes in temper-ature. Integrated heaters that provide local heating of individual microrings offer a method to correct for these effects, but no large-scale solution has been achieved to automate their tuning process. In this context, we present the use of dithering signals as a broad method for automatic wavelength tuning and thermal stabilization of microring resonators. We show that this technique can be man-ifested in low-speed analog and digital circuitry, lending credence to its ability to be scaled to a complete photonic interconnection network. Index Terms—Frequency locked loops, multi-processor inter-connection, optical interconnects, optical resonators. I