Optimize The Design And Temperature Stability Of The Wavelength Division Multiplexing Thin-film Narrow-band Filter

In response to the rapid development of optical communication technology,a lot of design problems in optical thin film need to be solved. In this paper the automatic optical thin film design methods are studied,design problems commonly met in optical communication systems are discussed and the problem of temperature stability of thin film are also discussed.In the paper,the development of optical thin film and optical communication system is summarized firstly. Then, we infer the thin film system reflection or the transmittance mathematics value formula and the characteristic matrix representation formula from the Maxwell's equations and the suitable boundary condition.We study the automatic design problem of optical thin film. An attempt is made to use the filled function as the modified function approach to apply global optimization to optical thin film problems. It is proved successful when applied to problems such as antireflection coatings and beam spliters.Meanwhile, it is also found that when the number of layers is fixed those local minima with less total optical thickness appear to be better. In the realization .Needle method are made to explore the impact of local optimization methods used,Parameter of these methods,the starting design,the search accuracy of function and the methods of thickness growth.In the discussion of design problems in optical communication systems, the design methods for WDM multiplex filter are provided and analyzed. Applying the ways of adjusting the bandwidth, minimizing the pass band ripples and group delay ripples, a 50GHz filter is designed.In the paper, we also discuss the temperature stability of DWDM thin film narrow band-pass filter. The calculating formulas of central wavelength drift based on thin film microstructure and thermal-stress deformation are deduced, the drift of DWDM filter 15 calculated with these formulas. It is also found that replacement of substrate and adjustment of film stack structure would lead to the change of drift,this will enhance the temperature stability of filter.Finally, summarization of all these works and advice for the future work are made in the paper.