IEEE 8- Instantaneous Microwave Frequency Measurement Using an Optical Phase Modulator


A novel technique for instantaneous microwave frequency
measurement using an optical phase modulator is proposed
and demonstrated. In the proposed system, a microwave signal
with its frequency to be measured is modulated on two optical
wavelengths at the phase modulator, with the phase-modulated
optical signals sent to a dispersive element, and detected at two
photo-detectors. Due to the chromatic dispersion of the dispersive
element, the two microwave signals will experience different power
fading, leading to different power versus frequency functions.
A fixed relationship between the microwave frequency and the
microwave powers is established. By measuring the microwave
powers, the microwave frequency is estimated. Compared with the
techniques using an intensity modulator, the proposed approach
is simpler with less loss. Since no bias is needed the system has a
better stability, which is highly expected for defense applications.
Experimental verification is presented.