Transmission Volume Holographic Grating-based Wdm Design

As a representation of high speed and great capacity transmission system, Wavelength Division Multiplexing (WDM) technology develops very fast in today's information era, and has had broad applications in world range. Dense WDM (DWDM) technology is widely used in long-distance backbone networks, and well meets the needs of bandwidth. So the bottle-neck of network's bandwidth has gradually changed to metropolitan area networks (MAN), the construction of MAN has become the main concern of network construction. With the unique advantages in the construction of MAN, Coarse WDM (CWDM) technology has attracted more and more attentions. Therefore, the research of the key equipments of WDM system is very important.In the present thesis, after comparing some advantages and disadvantages of several conventional kinds of WDMs, we present a detailed design method for the CWDM device based on the holography-grating technology. In Section 2, we give a physical insight for the mechanism of photorefractive holographic gratings and select some key factors, which should be considered in the process of the following design for the device with superimposed holographic gratings. Some important performance parameters (e.g., the diffraction efficiency, the sensitivity of wavelength and incident angle, and the polarization dependent loss (PDL)) of the CWDM device are theoretically analyzed using the coupled wave theory. Then the fabrication process of superimposed holographic gratings was introduced. In Section 3, Main structure parameters (e.g., the thickness of the crystal) and writing conditions (e.g., the incident angle) are also optimized to obtain both high diffraction efficiencies and low PDLs for the central channel using a rigorous coupled wave analysis method. Based on the final optimized results, an 8-channels CWDM device was designed. Numerical results show that the designed device has a good synthetical performance for each channel. In the last Section, the experimental method of the grating recorded is also introduced. We experimentally researched the impacts of the writing conditions such as recordinglight intensity and recording time. The thermally fixed methods of holographic gratings are also researched.Finally we indicated several following works in the designs and experiments and the application promise of the new technology is anticipated.