An Optoelectronic Oscillator for High Sensitivity Temperature Sensing

An optoelectronic oscillator (OEO) for high sensitivity temperature sensing is proposed and experimentally demonstrated. The oscillation frequency of the OEO is determined by a single passband microwave photonic filter (MPF) in the OEO loop, which is implemented using a broadband light source, a Mach-Zehnder interferometer (MZI), a dispersion compensating fiber, and a photodetector. One arm of the MZI is used as a sensing arm, which is exposed to temperature variations and the other arm is used as a reference arm. When the temperature is changed, the length difference between the two arms is changed, which leads to the change of the free spectral range of the MZI. Since the central frequency of the MPF is a function of the FSR, the oscillation frequency of the OEO is affected by the temperature variations. By measuring the frequency change, the temperature change to the sensing arm is estimated. The proposed approach is experimentally evaluated. High sensitivity temperature sensing with a sensitivity of 3.7 MHz/degrees C is experimentally demonstrated.