High-resolution low-noise microwave photonic interference mitigation filter

A new high-resolution microwave photonic interference mitigation filter with low-noise performance is presented. It is based on using a dual-input electro-optic intensity modulator together with a frequency-shifting amplified recirculating delay line loop. It can realise a very narrow notch, and also a wide and flat passband to simultaneously excise interference with minimal impact on the wanted signal. The interference mitigation filter can be integrated into optical fibre microwave transmission systems. Experimental results demonstrate a notch filter response having a very narrow notch bandwidth of 0.55% of the filter FSR, together with a wide and flat passband.