Tunable radio frequency photonic filter based on intensity modulation of optical combs

We demonstrate tunable programmable microwave photonic filters based on optical frequency combs. The utilization of optical comb enables to scale multi tap filters to large number of taps. By using optical line-by-line pulse shaping to program tap weights, we shape the filter's bandpass. In contrast to our previous work, we demonstrate a much simplified technique based on intensity modulator biased at its minimum transmission which results in double sideband with carrier suppression. We use a programmable optical delay line to uniformly tune the bandpass filter center frequency uniquely across half of the free spectral range. Our new scheme is very simple and easily implementable which provides filters with arbitrary tap weights. As an example we implement a filter with Gaussian apodized tap weights which we tune over 0–5.2 GHz with sidelobe suppression in the range 26–31 dB.