A Novel Approach to Realizing a Widely Tunable Single Passband Microwave Photonic Filter Based on Optical Injection

In this paper, a novel approach to realize a single passband microwave photonic filter (MPF) with wideband tunability based on an optical-injected distributed feedback (DFB) semiconductor laser is proposed and experimentally demonstrated. The fundamental principle is based on the wavelength-selective amplification of the DFB laser under optical injection. The frequency tunability, insertion loss, and out-of-band suppression ratio of the proposed MPF are investigated in the experiment. By varying the injection locking parameters, MPFs with the frequency tuned from 11 to 41 GHz are achieved, and the insertion losses and out-of-band suppression ratios are around 20 dB. They are useful in applications where high frequency and wideband tunability are required.