METHOD AND APPARATUS TO SENSE TEMPERATURE OF THERMAL TUNING ELEMENTS IN TUNABLE OPTICAL DEVICES

摘要

A tunable optical unit includes a resistive temperature device (RTD), a thermal tuning device and a measurement circuit. The RTD has a resistance dependent on a temperature of the thermal tuning device. The measurement circuit outputs a signal that is dependent on the resistance of the RTD. The signal is used to control the temperature of the thermal tuning device in tuning the tunable optical unit. A reference resistance can be connected in series with the RTD to make ratio-metric measurements to determine the RTD's resistance (and hence the temperature of the tuning elements) without having to know the value of the current conducted through the RTD and to reduce sensitivity to fluctuations in the excitation signal.