Noise investigation of a large free spectral range high-resolution microwave photonic signal processor

The noise components in a new microwave photonic signal processor that has the ability of simultaneously realizing a large free spectral range (FSR) and high-resolution bandpass filter response are investigated. The filter is implemented using the Vernier effect and the frequency-shifting technique in an optical delay line structure. The power spectrum of the signal-spontaneous beat noise, which is the dominant noise source in the system, is theoretically analyzed and experimentally measured. Experimental results are presented, which show that the new large FSR microwave photonic signal processor has a low-noise performance and demonstrate 31-fold increase in the FSR of a bandpass filter response while having a sharp passband and 30-dB stopband rejection level.