Optical approach for measuring unknown microwave frequency with improved sensitivity

We propose a novel photonic technique for unknown microwave frequency measurement by employing an optical group delay line. The 7-bit optical delay line composed of several magneto-optical switches and 1.6 km single-mode fiber is designed as a tunable dispersive medium in the measurement system. In our scheme, the measurable frequency range of 1 to 20 GHz with a measurement error less than +/-40 MHz was demonstrated experimentally. Also, we studied the sensitivity of the whole measurement system, and the minimum detectable power reached -50 dBm. (C) 2013 Society of Photo-Optical Instrumentation Engineers (SPIE) [DOI: 10.1117/1.OE.52.2.025002]