Based On The Holographic Volume Grating Tunable Narrowband Optical Filter

Optical fiber communication is one of the most important technologies, which is supporting the rapid growth of communication, and is becoming the prop of modern communication. WDM is an effective method to enlarge the capacity of optical fiber communication and to use fully optical fiber bandwidth. And in WDM, the tunable narrow-bandwidth filters are necessary. In this article, we introduce a new method of design of this kind of filters, which are based on reflection volume holographic gratingsAt first, from the principle of the photorefractive effect, we analyze the physical mechanism and characters of the photorefractive effect. And the photorefractive effect in LiNbO₃ crystal is discussed. And then we discuss the experimental method of the recording and thermally fixing of the reflection volume holographic gratings, from the discussion of volume holograms.In the optimal design of the filter, we design the reflection volume holographic grating at first. Based on the coupled-wave theory of Kogelnik, the grating is optimizing on the diffraction efficiency, PDL and the bandwidth. And we get the best length and incident angle. And then we analyze performance of the grating, such as the diffraction efficiency, the PDL. At last, we optimize the dimension of whole system, according to the requirement of the fiber-optical networks.And we also do research of the experiment of the grating. The choices of the recording material, light source and the ratio of the recording light are discussed. By experiments, we analyzed the impact of recording time and the intense of the recording light on the diffraction efficiency. In the thermally fixing process, we chose the fixing temperature and time. At last, we experimented on the grating to research its performance and discussed the result briefly.At last, we made a summary of our work in the article and gave some new advice on the design. And we analyzed the foreground of the volume holographic gratings.