Contents I. Introduction
Microwave Photonic Filter (MPF) is a powerful technique for implementing signal processing functions of microwave signals [1]–[11]. It offers the advantages of low loss, wide bandwidth, tunability, and reconfigurability. Current implementations of the MPF mainly use a single incoherent light source with coherent time smaller than the minimum delay time of the filter to ensure stable filter operation [1]–[3]. However, its performance is limited by phase induced intensity noise. In addition, delay tuning can be difficult which limits the reconfigurability of the filter. Multisource MPF offers much promise. However, finding a suitable light source has been a challenge. Previous demonstrated schemes in this direction include the use of independent lasers operating at different wavelengths [4], spectrum slicing the output of a broadband source [5], [6], and the use of output spectrum of an Fabry—Pérot (F-P) laser [7]. The main problem associated with the first approach is the high cost when a large -value is to be achieved. Spectrum slicing will introduce large amplitude noises. Variation of mode power distribution in the F-P laser has limited its usefulness in filter implementation. Although there was an attempt of using multiwavelength laser for the implementation of MPF, the limited performance of the laser has limited the performance of the MPF filter [8].
