Optically Controlled Fast Reconfigurable Microwave Photonic Dual-Band Filter Based on Nonlinear Polarization Rotation

A high-speed optically controlled microwave photonic (MWP) reconfigurable dual-band filter is presented, which is achieved using a Lyot loop filter for spectrum slicing and ultrafast nonlinear polarization rotation (NPR) effect in a semiconductor optical amplifier for high-speed tuning. Through the control of optical pump power, the MWP filter is switchable between four different operation states-all-block state, dual-band state, and single-band state with two different passband frequencies. The use of NPR greatly increases the tuning speed of the MWP filter to gigahertz range, making it capable for high-speed tuning in dynamic multiband applications. The four operation states and high-speed adjustment significantly improve operation flexibility of the filter. Furthermore, good passband quality is also obtained that the sidelobe suppressions of both passbands are over 40 dB with clean and sharp passband profiles, providing good filter selectivity.