Fig. 1. Schematic diagram of the proposed microwave photonic filter. TLS, tunable laser source; PC, polarization controller; PM, phase modulator without a polarizer; MRR, micro-ring resonator; PD, photodetector; VNA, vector network analyzer.

Fig. 2. Normalized magnitude and phase response of the MRR. Inset: the MRR used in the experiment.

Fig. 3. (a)–(c) Measured optical spectra of the optical signal output from the chip by adjusting the PC2. (d) The calculated relationship between the power ratio of the +1st and −1st sidebands and the phase factor φ of PC2.

Fig. 4. Measured beat signal spectra of the light output from the chip by adjusting PC2. Inset: the corresponding optical sideband spectra.

Fig. 5. Normalized frequency response of the MPF (a) band-stop filter and (b) band-pass filter (solid blue line, measured results; red dash line, simulated results). The optical spectra of the modulated signal at the MPFs’ center frequency: (c) band-stop; (d) band-pass.

Fig. 6. Normalized frequency responses of the MPFs with different center frequencies when the MPF is operating as (a) the band-stop filter and (b) the band-pass filter.