Theoretical investigation of a photonic-assisted instantaneous frequency measurement with a tunable measurement range and resolution by adjusting the chirp parameter of an optical intensity modulator.
The chromatic dispersion-based frequency-to-power mapping approach is often used in microwave photonic (MWP) instantaneous frequency measurement (IFM) receivers. A mechanism to tune the measurement range and resolution of these MWP IFM receivers by adjusting the chirp parameter of their optical intensity modulators is proposed and demonstrated. In particular, an MWP IFM receiver with a tunable measurement range and resolution based on a chirp-adjustable dual-drive Mach-Zehnder modulator (DDMZM) and two dispersive mediums is proposed and theoretically investigated. In the proposed MWP IFM receiver, a radio frequency (RF) signal whose unknown frequency is intended to be measured is applied to the two arms of a DDMZM with an appropriate power ratio. By adjusting the ratio of the two applied RF signals, the chirp parameter of the DDMZM and consequently, the measurement range and resolution of the MWP IFM receiver, can be tuned. The analytical results are verified by simulation results using commercial software. The proposed method also can be used in most of the previously reported MWP IFM receivers based on the chromatic dispersion and frequency-to-power mapping approach to tune their measurement ranges and resolutions.