Tunable microwave photonic notch filter using on-chip stimulated Brillouin scattering

We report the first demonstration of a tunable microwave photonic notch filter based on stimulated Brillouin scattering (SBS) in a photonic chip. Single-sideband with carrier modulation (SSB+C) scheme was used to map the SBS loss spectrum into a frequency notch in the RF domain. The notch frequency can be tuned by modulating the SSB+C signal onto a tunable carrier, which was generated by means of SSB suppressed-carrier (SSB-SC) modulation. The notch filter has a high-resolution with 3-dB and 6-dB bandwidths of 126 MHz and 78 MHz, respectively. The filter has a notch depth of 20 dB, and the notch frequency can be continuously tuned over a range of 2-8 GHz, which is limited only by the current measurement setup.