Study On All Optical-Band Of Thin Film Filter Applicated Coarse Wavelength Division Multiplexing System

With the acceleration of the construction of the MAN(Metropolitan Area Network),theinformation transmission of more higher speed and more larger capacity becomes more andmore popular. People want to get the better network services, but also want to have a lowerconsumption costs. In this background, CWDM(Coarse Wavelength Division Multiplexing)which has lower cost,higher rate and better adaptability has been increasingly widely used.In this paper, we designed single-channel thin film filter and multi-channel thin film filter byusing Fabry-Perot filter,and the two thin film filters will be used in CWDM system.We alsodesigned a CWDM system architecture to test performance of the multiplexer/demultiplexerof the film filter, and made a high-rate CWDM transmission system architecture to lay thefoundation for the further expansion.In the single-channel thin film filter design, I also used common materials Ta2O5andSiO2as reflection films. In order to design a better filter,I firstly analyzed the single-channelcharacteristics,including different refractive index between high and low, different fringeorder, different reflective layers, different number of cavities, different angle of incidence.On this basis,I determined some of the better performance of the basis layer structure bymathematical calculation method, then compared these film structure to determine arelatively optimal solution.And we made18single-channel thin film filters by this way,too.In the design of the multi-channel thin film filter, I used the design of balanced structureto constitute WDM multiplexer/demultiplexer to make it more rational, this structure canefficiently reduce the insertion loss.In order to improve design’s efficiency and enhancefilter’s performance,I firstly analyzed its characteristics,including different intervals layerthickness of impact on the channel spacing, different interval thickness on ripple, reflectivefilm department of impact on the bandwidth, the different position of the spacer layer ofimpact on the bandwidth and ripple. On this basis, I put forward the basic structure of the8-channel multiplexer/demultiplexer, then, made a8-channel optimum structure forcomparative analysis to design a8-channel multiplexer/demultiplexer.I designed the structure of CWDM system after finishing the design of thin filmfilter.the8-channel multiplexer/demultiplexer is be used and tested in CWDM system.It wasproved that the balanced structure thin film filter is better than ever through comparing the CWDM system technical standard. At the same time,a high rate CWDM transmission systemhave been designed to solve the capacity of CWDM.