Fig. 1. Optical spectra of the phase-modulated signal and the flattop optical filter when the frequency of the optical carrier is tuned (a) aligned with the center of the optical filter and (b) away from the center of the optical filter.

Fig. 2. Structure of the photonic chip.

Fig. 3. Simulated results of (a) output at the drop port of the 10th-order MRR and (b) proposed MPF with adjustable bandwidths.

Fig. 4. Optical micrograph of the fabricated device.

Fig. 5. Experimental setup of tuning the 10th-order MRR. BOS, broadband optical source; PBS, polarization beam splitter; PC, polarization controller; OSA, optical spectrum analyzer.

Fig. 6. Optimized optical filter at the drop port.

Fig. 7. Experimental setup of the proposed MPF. LD, laser diode; PC, polarization controller; PM, phase modulator; EA, electronic amplifier; VNA, vector network analyzer.

Fig. 8. (a) Measured dark current of the Ge PD; (b) measured response of the Ge PD.

Fig. 9. Optical spectra of the bandpass filter and the phase-modulated signals after the filter.

Fig. 10. Measured frequency responses of the proposed MPF with different bandwidths.