Wavelength Locking and Thermally Stabilizing Microring Resonators Using Dithering Signals

Abstract

Abstract-The bandwidth bottleneck looming for traditional electronic interconnects has driven the consideration of optical communications technologies as realized through the complementary 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 network while offering superior energy-efficiency and small footprint characteristics. However, silicon microring-based structures have a large susceptibility to fabrication errors and changes in temperature. Integrated heaters that provide local heating of individual microrings offer a method to correct for these effects, but no largescale 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 manifested 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 interconnection, optical interconnects, optical resonators.

A Micro-Processor-Based Feedback Stabilization Scheme for High-Q, Non-Linear Silicon Resonators

“…There have been a number of demonstrations of cavity stabilization in silicon photonic devices using both electrical [14] and thermal [15] elements on-chip. These schemes have been primarily designed for tracking of the cavity line in linear optical applications such as data communications.…”

“…The cavity wavelength tuning mechanism used in this work is achieved by fabricating a thermal tuning element above the grating device, as shown in Figure 2a. By applying a voltage across the heater element, localized temperature variations can be applied to the device and therefore control exerted over its resonance wavelength [11,14]. The devices fabricated in this work were produced on a SOI wafer (SOITEC, Bernin, France) with a 220 nm thick silicon core.…”

On-Chip OSNR Monitoring With Silicon Photonics Transparent Detector

“…Integrated detectors allow for diverse functions on a chip including, but not limited to, routing and switching of optical channels [1], [2], self configuring PICs [3], thermal tuning and wavelength locking of filters and modulators [4], [5]. In practical applications, most of these functions require the identification, monitoring and manipulation of optical signals regardless of the presence of other channels and/or optical noise.…”

Fast wavelength locking of a microring resonator

“…They are also susceptible to power fluctuations in the optical path. An alternative wavelength locking technique has been demonstrated based on the generation of anti-symmetric error signals using thermal dithering [4]. This method offers implementation using simple, low-cost, and low-power analog electronics, and is immune to fluctuations in optical power.…”