A new microwave photonic instantaneous frequency measurement system that can simultaneously measure multiple-frequency signals while achieving very high resolution and wide frequency measurement range is presented. It is based on the frequency-to-time mapping technique implemented using a frequency shifting recirculating delay line loop and a narrowband optical filter realized by the in-fiber stimulated Brillouin scattering effect. Experimental results demonstrate the realization of a multiple-frequency measurement capability over a frequency range of 0.1-20 GHz that can be extended to 90 GHz, and with a measurement resolution of 250 MHz.
Nguyen, T. H. A., Chan, E. H. W., & Minasian, R. A. (2014). Instantaneous high-resolution multiple-frequency measurement system based on frequency-to-time mapping technique. Optics Letters, 39(8), 2419-2422. https://doi.org/10.1364/OL.39.002419