The Numerical Study Of A Chaotic Fiber Bragg Grating Quasi-distributed Sensing System

Due to unique wavelength encoded character, fiber Bragg grating has now become an important component in fiber sensing and fiber communications. Light source is usually optical pulses. The input pulse width should shorter than the round trip time between the two adjacent FBGs to allow the separation of reflected light in the time domain. The FBGs are difficult to dense multiplexing owing to dead zone.Based on a chaotic laser as well as identical low reflectivity FBGs, a novel quasi-distributed optical fiber sensing system has been proposed and theoretically analyzed. The works have been carried out as follows:1. Application, characteristics and future prospects of optical fiber sensing are introduced. The advantages and disadvantages of distributed sensor networks are discussed. Multiplexing and demodulation of several common optical fiber sensor networks have been analyzed.2. Coupled-wave theory is used to analyze reflectivity and wavelength of FBG:Sensing principle analysis of temperature, stress and pressure are discussed.3. The history of chaos is summarized. We analyzed routes to chaos and the basic principles of generate chaos.4. We give diagram of the proposed system and illustrate demodulation principle of the proposed system. The numerical simulation for sensing systems is demonstrated. The relationship between the multiplexing capability and multi-reflection signals is discussed. The spatial resolution influenced by the bandwidth of chaos is analyzed.