Study On Tunable Microwave Photonic Filter With High Shape Factor

Microwave photonic filter combines the advantages both of microwave communications and fiber optic communications, which makes electromagnetic waves can process in the optical field with high transmission speed, low cost, small size, low loss, high immunity to electromagnetic interference. In future microwave photonic filter may have broad application in the communication system. Currently basic researches on microwave photonic filters focuses on the new filter structure, high quality factor, the negative coefficient and tunable, reconfigurable factor. This paper focuses on a new type of tunable microwave photonic filter with high shape factor, which outline is as follows :Basic principle of microwave photonic filter is introduced. Based on the coherence properties, the reconfigurability and the tunability, microwave photonic filter is proposed, which lays the foundation for a high rectangular microwave photonic filters below.A negative coefficient microwave photonic filter structure is introduced based by the SOA XPM effects, and its simulation with software proves its feasibility. The research describes the cascade theory. By FIR cascading with FIR and IIR filters, respectively, a filter with high Q value is achieved. Using software simulation of the cascade theory for improves the quality factor of feasibility;Through the study of flat microwave photonic filter, a microwave photonic filter with high shape factor is introduced, which implemented a three-tier cascade filter. The first part is made by TTNC-FIRMPF with a SOA, and the second part is made by OO-IIRMPF constituted by a high quality factor sector achieved by FIR and IIR filters cascading. By mutual compensation of the peaks and troughs of the wave the filter gets the flat top and steep sideband of the filter. The research elaborates the effect on the high shape factor with three filter coefficients and analyzes the feasibility of adding three tunable fiber delay line filter to achieve a tunable filter.