Microwave Photonic Sensor Based on Optical Sideband Processing with Linear Frequency-modulated Pulse

In this paper, a new microwave photonic (MWP) sensing scheme, which is based on interrogating microresonator sensors with fast speed and improved resolution by adopting a broadband linear frequency-modulated pulse (LFMP) in the MWP sideband processing, is presented. The LFMP modulates the interrogation light, creating the optical sideband that sweeps through the resonance rapidly. By using the optimized DC bias point, the resonance spectral dip with arbitrary characteristics can be transformed into the zero point in the temporal envelope of the transmitted LFMP, hence providing improved interrogation resolution of the resonance shifts caused by environmental changes. The proposed scheme was implemented with a microdisk resonance for temperature sensing, where up to 20-fold interrogation resolution improvement was demonstrated by tuning the DC bias voltage to the optimum. The interrogation speed is 500 kHz, which can be further improved by using a shorter repetition period and pulse width.