Nonlinear Fiber Grating And Its Application

The generation of ultra-short optical pulse is one of the key techniques in the high-speed optical time-division multiplexing(OTDM) system. The higher the transmission speed is, the shorter the optical pulse width is expected to be. Nowadays, the optical pulse used in the OTDM system is often generated by the gain-switched distributed-feedback (GS-DFB) semiconductor laser, which has a large pulse width and negative chirp. Therefore, in order to satisfy the demand of the OTDM system, the technique of pulse compression must be adopted. Based on the previous works, many feasible schemes about pulse compression have been proposed and investigated in this paper, through which the pulse can be compressed effectively.In this paper, we focus our research on the basic theory of optical pulse compression, fiber Bragg gratings (FBG) and their applications in optical pulse compression. The main work includes:1. The transmission properties of optical pulse are introduced. Following upon summarized the development of optical communication and optical pulse compression technical, the nonlinear coupled mode (NLCM) equation and NLS equation which are used to describe the optical pulse' s transmission properties in FBG are investigated. At last, the numerical solution of these equations—split step Fourier method (SSFM) is carried out.2. The optical pulse compression technical based on FBG is investigated. From the role the FBG plays in the compressor, we introduce some optical pulse compressors. Their advantages and disadvantage are investigated and the improvements are carried out.3. A new compress method based on interact on of solitons is investigated. Following upon the introdu(?)tion of Bragg soliton, the excitation of in-gab solitons which are solitons with a spectral content located mostly within the gap, or the forbidden bandgap is discussed. We investigate a new excitation method which based on interaction of in-gap solitons to solve the issues of excitation of in-gap solitons, which are high intensity of incident pulse and reflection of gratings. In progress of our research, we found that the width of output pulse is shorter than incident pulse. The compression factor is about two orders of magnitude higher than previous works.The above results can provide an instructive insight to obtain ultra-short pulse.