Single passband microwave photonic filter with widely tuning range based on optical injected distributed feedback semiconductor laser

A novel widely tunable single passband microwave photonic filter (MPF) is proposed and experimentally demonstrated, which is based on a carrier-suppressed double sidebands (CS-DSB) optical signal injected into an distributed feedback (DFB) laser. A polarization modulator (PolM) and a polarization beam splitter (PBS) are exploited to generate the CS-DSB optical signal. When the CS-DSB optical signal is injected into the DFB laser, due to the frequency selective gain feature of optical injected DFB laser, one sideband of the CS-DSB optical signal is selected and amplified. Beating the amplified sideband with the optical carrier, the gain spectrum of the DFB laser is mapped to the frequency response of the MPF. The MPF can be tuned by adjusting the wavelength of the DFB laser. Experiment results show that the MPF can be tuned from 0 to 40 GHz by changing the working temperature of the DFB laser.