Instantaneous microwave frequency measurement using a microfiber ring resonator (MRR) based photonic differentiator

A novel photonic approach for the instantaneous microwave frequencies measurement (IFM) using microfiber ring resonator (MRR)-based photonic differentiator is proposed and experimentally demonstrated. A square and monotonic relationship between the amplitude comparison function (ACF) and the frequency of the incoming microwave signal is established and used for the microwave frequency estimation, with a capability of wide measurement range. Since the MRR can be fabricated flexibly and only one light source, one modulator and one photodetector are needed, the complexity and cost of the proposed IFM system is considerably reduced. A proof-of-concept experiment has been performed with a measurement error less than ±0.4 GHz over the frequency range 0.5–12 GHz.