| Optical fiber communication is the most active technology of communication field. Optical fiber communication, satellite communication and mobile communication are the three main orientations of modern communication technology. At present, plenty of communication business continuously emerges, especially fast development of Internet induces rapid increase of communication capacity. Thus, it is necessary to establish large-capacity and high-speed optical fiber communication system. Fiber gratings provide possibilities for the further development of large-capacity and high-speed optical fiber communication system. Fiber grating is a new kind of all-fiber passive device that results from that the refractive index of optical fiber core is periodicity microperturbation. Because of the excellent properties such as compatible with optical fiber, easy fabrication, little insert loss, small volume and low price, fiber gratings have wide application in optical fiber communication and sensor field. Thus, since the successful fabrication of first fiber grating, the fabrication and application of fiber gratings is central issue of interest all along. Chirped fiber grating is one type of fiber gratings whose optical period (product of grating's effective refractive index and refractive index microperturbation's period). Light with different wavelength is reflected at axial different point of chirped fiber grating. So chirped fiber gratings have broad reflection bandwidth. The group delay in chirped fiber grating reflection bandwidth changes gradually. These properties are what other type fiber gratings do not have. It is these unique properties that make chirped fiber gratings have unique applications both in optical communication and sensor field, such as filters and dispersion compensators. Tilted fiber grating is another type of fiber gratings with an angle between the fringes and the normal to the fiber axis. There are many kinds of coupling in tilted fiber grating because of existing of the angle. The special properties of tilted fiber gratings, such as lower Bragg reflection, make the gratings have special applications.The work of this thesis is deeply studying the principle, fabrication properties and applications of chirped fiber gratings (including chirped sampled fiber gratings) and tilted fiber gratings. The main achievements of this thesis are shown as following:High quality chirped fiber gratings were fabricated by the method of using phase mask, in which we used a chirped phase mask and once scanning explore technique to fabricate chirped fiber gratings. In experiment, a 100-mm apodized linearly chirped fiber grating was obtained that has more than 99% reflectivity, linear group delay in reflection bandwidth of 0.4nm, dispersion of about -2403ps/nm, ripple of delay of less than +/-20ps. The grating can compensate 140 km long fiber in 10Gb/s system, and it has been advanced in the nation. In addition, the linearly or nonlinearly chirped fiber gratings with fixed wavelength centers were fabricated by the methods of heating coils and bending plate using fiber Bragg gratings; the linearly or nonlinearly chirped sampled fiber gratings were also obtained by the methods of fiber etching and bending plate using uniform sampled fiber gratings.We firstly proposed to fabricate chirped fiber grating filters with different designed spectra using a wideband chirped phase mask and scanning explore technique. The designed spectrum of the filter was analyzed using the software (we reserved the copyright). Then the functions of the wavelength and intensity of the spectrum were converted to the controlling function during the explore process. The chirped fiber grating with spectrum same as the designed filter was fabricated by scanning explore controlled by the function. In experiment, the chirped fiber grating with uniform reflectivity in the range of 40 nm was obtained. Particularly, we successfully fabricated EDFA gain flattened filters (GFF) based on the chirped fiber gratings using the method. The v...
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