Research Of All Fiber Flat-top Interleaver

The development of optical communications have been promoted greatly by WDM (wavelength division multiplexing). Optical net based on WDM technology is becoming the main transmitting platform in telecom net and internet. In WDM, with the counts of channel increasing, the spacing of channel decreases. Which challenges the traditional filter technologies greatly. So the existing filter technology can't satisfy the demand of the system in present. For solving this problem, a novel optical apparatus—Interleaver is proposed. Interleaver makes it possible for the traditional filter technologies to perform the their functions in the new applications. After several years'research and development, Interleaver has been developed rapidly, and Interleavers were already used in some fields.Firstly, we introduce Bragg fiber grating and its manufacturing methods, and Mach-Zehnder interferometer's principle, manufacturing methods as well. Secondly, we introduce the methods for manufacturing Interleaver and their merits and demerits briefly.Thirdly, we focus on proposing a novel all-fiber flat-top Interleaver. Linking the two outputs of the second coupler of Mach-Zehnder interferometer simply by fiber makes the new Interleaver. When k=0.2, it can achieve up to 55% efficiency of usable bandwidth, while its ripple is little, 0.174dB; good dispersion compensation ability and infinite isolation in theoretically. Compare to the traditional MGTI, it is all-fiber; compare to MZI, its structure is simple and its output spectrum is flat-top. So we think it is a very good Interleaver.Finally, we propose a method for optimize the Fourier Flat-top Interleaver, it makes the design of F3T Interleaver simple. By simulation study, we found it possess good performances, so it is useful for practical F3T Interleaver design.