Fast Wavelength Locking of a Microring Resonator

Abstract — Microring resonator devices require thermal initialization to match their intended operating wavelengths in a process called wavelength locking. We use the dither technique, where we apply a small periodic signal to the microring’s integrated heater, to demonstrate reliable wavelength locking of a microring resonator filter to an operating wavelength at a wavelength shift rate of 0.012 nm/µs, an order of magnitude faster than previous demonstrations. We also identify and charac-terize fundamental speed limits of the wavelength locking process, showing that the integrated-heater bandwidth is the limiting factor. Index Terms — Optical interconnections, silicon photonics, microring resonators, control systems