Lossless and high-resolution RF photonic notch filter

A novel technique to create a lossless and tunable RF photonic bandstop filter with an ultra-high suppression is demonstrated using the combination of an overcoupled optical ring resonator and tailored stimulated Brillouin scattering gain. The filter bandwidth narrowing is counterintuitively synthesized from two broad optical resonance responses. Through a precise amplitude and phase tailoring in the optical domain, the RF filter achieves a minimum insertion loss (<0 dB), a high isolation (>50 dB), and a tunable 3 dB bandwidth (60-220 MHz) simultaneously with wide frequency tunability (1-11 GHz). This ultra-low loss RF filter paves the way toward broadband advanced spectrum management with low loss, high selectivity, and improved signal-to-noise ratio.