Flat-top bandpass microwave photonic filter with tunable bandwidth and center frequency based on a Fabry-Pérot semiconductor optical amplifier.

Optics letters

PubMedID: 27420520

Jiang F, Yu Y, Cao T, Tang H, Dong J, Zhang X. Flat-top bandpass microwave photonic filter with tunable bandwidth and center frequency based on a Fabry-Pérot semiconductor optical amplifier. Opt Lett. 2016;41(14):3301-4.
We propose a flat-top bandpass microwave photonic filter (MPF) with flexible tunability of the bandwidth and center frequency based on optical nonlinearities in a Fabry-Pérot semiconductor optical amplifier (FP-SOA). Phase-inverted modulation induced by cross-gain modulation (XGM) and optical spectral broadening induced by self-phase modulation (SPM) are exploited to achieve flat-top and bandwidth tuning, respectively. Wideband and continuous tuning of the center frequency is achieved by altering the bias current of the FP-SOA. Experimental results demonstrate a flat-top single-passband MPF with its center frequency tunable from 6. 0 to 18. 3 GHz by adjusting the bias current from 54. 05 to 107. 85 mA. The 3-dB bandwidth of the passband when centered at 10. 0 GHz is shown to be variable from 680 to 1. 43 GHz, by increasing the injected optical power from -1 to +5??dBm. During the bandwidth tuning, the amplitude ripple within the passband is maintained at less than ±0. 5??dB. Excellent main to secondary sidelobe ratio exceeding 45 dB is achieved when the MPF is centered at 18. 3 GHz.