In one embodiment of the present invention, an apparatus operates a control loop
for a tunable optical device. A digital reference signal is converted to an analog
reference signal and then introduced into the optical path of the tunable optical
device. An analog feedback signal, corresponding to the digital reference signal,
is recovered from the tunable optical device. The analog feedback signal is converted
to a digital feedback signal. The apparatus sends tuning information to the tunable
optical device based on analysis of the digital reference signal and the digital
feedback signal. In one embodiment, the tuning information is used for wavelength
locking of the tunable optical device. In another embodiment, the operation of
the control loop is synchronized with another function of the tunable optical device.
