Key Techniques And Software Design Of Optical Wavelength Monitoring Unit In DWDM System

Along with the current of global information revolution surging, it has become a focus of concern that how to build a high-speed broadband communications network. The issue that the scale and bandwidth of existing communications network do not adapt to the rapid growth of the communications services has been solved by the employment of the DWDM. The frequency interval between optical channels is being reduced to 50GHz, even 25GHz in DWDM system. To separate the communications services, higher requirement for the stability of laser wavelength has been brought forward. Therefore, the corresponding optical wavelength monitoring technique has become a research hotspot. The optical wavelength monitoring (OWM) unit appears in this background.This paper encloses the application of OWM in DWDM transmission system, takes the techniques of wavelength monitoring in centralized mode and wavelength feedback control as the research objects, launches a more in-depth and extensive research, and achieves some innovative research results. The wavelength monitoring in centralized mode has been realized by the application of tunable filter. Compared with the distributed mode, it avoids disposing a single wavelength locker in each OTU, thus reduces the cost of the system greatly. The wavelength locker application and the wavelength examination algorithm improve the central frequency deviation measurement precision of the carriers to±4GHz. The utilization of the wavelength feedback control technique makes the wavelength automatic tuning come true, the capture range achieve 5～10GHz, and the tuning precision achieve 2GHz. The high performance of OWM has satisfied the DWDM system performance requirement very well.The paper includes six chapters. In chapter 1, the background of the OWM is introduced. Then, the principle and disposition in DWDM system, technique innovation and key algorithm in software design are showed in chapter 2. Next, software unification processing frame is introduced briefly, and the main global variables and the key data structures in software design are explained with emphasis in chapter 3. The interfaces design of each module in the software design, and the processes of wavelength monitoring and automatic tuning are elaborated in detail in chapter 4 and chapter 5. Lastly the achievements of technique innovation are summarized and further improvements requests of the next version are explained in chapter 6.