Phase Summation Analysis On Photorefractive Volume Grating And Its Applications In Wavelength Division Multiplexing

With the rapid development of computer network communication and information processing, Wavelength division multiplexing (WDM) technology is one of the most important techniques to enlarge the transmission capacity by utilizing the present fiber systems.WDM means the technique that the low-loss window of an optical fiber can be divided into some channels according to the separation of angles or frequencies, each wavelength channel occupies a bandwidth of a fiber, and multi-wavelength optical signals are transmitted in one optical fiber simultaneously.By using the photorefractive properties of photorefractive materials, multiple volume holographic gratings can be stored in recording materials with optical holographic methods, wavelength components of multi-wavelength signal beams can be respectively Bragg diffracted by the corresponding gratings and separated, and consequently, WDM is achieved.The coupled wave theory can be used to analyze some grating parameters, including the diffraction efficiency of holographic gratings, but it's useless for analyzing the bandwidth of diffracted beams. Each channel of diffracted beams has the same bandwidth, which means each channel of diffracted beams carries the same amount of information. And this is of great significance to WDM. To analyze the bandwidth of diffracted beams and make each channel has the same bandwidth, the method of phase summation is presented in this thesis.Firstly, the photorefractive effect and its microscopic mechanism are analyzed in this thesis. Two kinds of volume holographic gratings and their Bragg diffraction are discussed. Moreover, reflection gratings are analyzed with coupled wave theory. And the principle of WDM based on reflective volume grating is presented.Secondly, the method of phase summation is presented, and with which the diffraction of non-slant gratings is analyzed. We solved the diffraction efficiency with the method of phase summation, and discussed the selectivity of angle and wavelength. For a more general case, the slant grating are also calculated and...