On-chip wavelength locking for photonic switches

We present an on-chip wavelength reference with a partial drop ring resonator and germanium photodetector. This approach can be used in ring-resonator-based wavelength-selective switches where absolute wavelength alignment is required. We use the temperature dependence of heater resistance as a temperature sensor. Additionally, we discuss locking speed, statistical variation of heater resistances, and tuning speed of the switches.