Wideband tunable single passband microwave photonic filter based on optical injection

Optical injection is an effective way to generate a tuned microwave photonic filter (MPF). However, the tuning range of the optical injection-based MPF is limited by the nonlinear dynamics and the nonideal roll-off optical filter. To enlarge the tuning range of the MPF, a polarization modulated optical signal injection distributed feedback semiconductor laser is employed. The method is free from the nonlinear dynamics and the nonideal roll-off optical filter. The experimental result shows that the proposed MPF can be tuned from 0 to 40 GHz by directly tuning the center wavelength of the optical carrier. The tuning range can be increased if polarization modulator and photodetector with larger bandwidth are exploited. To the best of our knowledge, this is the largest frequency tuning range of optical injection-based MPF.