Tunable and flat single-notch microwave photonic filter with multi-wavelength optical source

A tunable and flat single-notch microwave photonic filter (SNMPF) with a multi-wavelength optical source is proposed and demonstrated. In the experiment, the multi-wavelength optical source is based on a tunable laser and a broadband optical source, which has the ability to achieve separate control of the first tap and secondary taps. Through a large number of tap amplitude tests and simulations, the filter can achieve a flat-passband; the passband ripples are smaller than 0.65 dB. The notch depth of the SNMPF is tuned by changing the amplitude of the first tap. The frequency of the SNMPF is continuously tuned by controlling the Fourier-domain optical processor to induce an additional phase, and the 3 dB bandwidth of the filter is tuned by controlling the waveshaper to adjust the number of taps. For simulation results, the depth of the SNMPF is tuned from −43 dB to −14.73 dB, the center frequency is tuned continuously from 0 GHz-74.488 GHz, the bandwidth with 10-taps is 3.54 GHz and the SNMPF has a flat-passband.