Wavelength locking of a Si ring modulator using an integrated drop-port OMA monitoring circuit

We demonstrate wavelength locking of a hybrid C MOS-silicon photonics ring-based transmitter through direct monitoring of the optical modulation amplitude (OMA) at the drop port of the ring modulator. The OMA is read from a Ge photodetector by a low-power 40nm CMOS circuit, which subsequently drives a feed-back loop that controls the modulator temperature using an integrated heater. OMA stabilization is demonstrated under abrupt laser wavelength variations of up to 150pm, under dynamic modulation at 2Gb/s.