Detailed Theoretical and Experimental Study on Single Passband, Photonic Microwave FIR Filter Using Digital Micromirror Device and Continuous-Wave Supercontinuum

We perform a detailed theoretical and experimental study on the impact of the finesse (F) of a multiple wavelength channel optical filter on output microwave filter transfer function in a spectrum slicing-based photonic microwave finite-impulse response (FIR) filter. For this paper, we use the combination of a digital micromirror device-based spatial light modulator and a continuous-wave, depolarized supercontinuum, since it allows us to perform flexible reconfiguration of output filter transfer function. It is found that the superimposed broadband, low-pass RF transfer function induced by the wide linewidth single-wavelength channel effectively suppresses higher order, periodic resonance peaks as the F is reduced. The optical filters with F=2 are found to provide the most effective suppression of higher order peaks, whatever the single channel waveform is: sinusoidal or Gaussian.