Theory And Application Analysis Of Fiber Grating And Tandem Gratings

Some type of fiber light source with broad band and smooth power chart is needed for Fiber Gyroscope. The output power must be smoothed before used. Fiber grating is widely used in Fiber Laser and Optic communication and so on. The coupling-mode theory is deeply studied, and the application of series of fiber gratings in smoothing optic fiber source is analysed. The main work is provided as follows:1. The coupling-mode theory in nonuniform wave-guide is expatiated, used for the analysis in fiber gratings and FBG2. The coupling-mode theory in Long-period grating is used to set up calculational method. The transmission spectra of the LPG is simulated by means of using programmes. The calculational method is proved accurate compared with the result from professional software.3. It is analysed through mathematic simulation how the characteristics of LPG is affected by its structure parameters. The rules how the transmission spectra of LPG changes with different transverse size or refractive index of fiber is discovered.4. Theory model is built up for series of fiber gratings. Several series of fiber gratings is designed aim at different kinds of power spectra, and the smoothed spectras are obviously improved so that they will be useful in fiber gyroscope.