| In response to the rapid development of projector display and 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 optical stability of thin film are also mentioned. The research work in this paper is as follows.1. Study on 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 beamspliters. 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 of the Needle method, efforts are made to explore the impact of local optimization methods used, parameter of these methods, the starting design, the search accuracy of P function and the methods of thickness growth. Through theoretical analysis and experiments, it is found that the efficiency and speed of Needle method depends largely on local optimization method use. The scaled BFGS type variable metric method performs well in optical thin film optimization. The accurate search of P function is not necessary. Generally, the larger the total thickness of the starting design, the better the results. Different types of starting design cause the result to vary. For antireflection coatings, the starting structure of iH leads to best outcome. When the process of Needle optimization is trapped in a local minimum, it is pulled out by increasing the thickness of the current structure. Several ways of increasing the thickness are proved to be successful yet the one that increases the merit function least appears to be most efficient.2. 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 passband ripples and group delay ripples, a SOGHz filter is designed. The Needle method is applied to the design problem of gain flattening filter and the result is flat with a tolerance of +-0.5dB. In order to design the transparent electrode used in C band, the Drude approach is used to calculate the refractive index of ITO. The calculated transmittance and the measured one vary less than 1%. Using the method applied in design of induced bandpass filters, a C band transparent electrode of 92% transmittance is designed and produced. A liquid crystal optical switch whose insertion loss less than 0.4dB is also produced.3. In the study of optical stability of optical filters, it is found that the observed central wavelength shift of a filter cannot be perfectly explained by the moisture absorbed in the columnar structure of thin film and the stress between film and substrate. So this paper suggests that the temperature coefficient of refractive index of water absorbed in the columnar structure contributes to the central wavelength shift of optical filters. The suggestion and the experiment data meet well.The innovation of this paper can be expressed in 6 points:1. 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 beamspliters. Meanwhile, it is also found thatwhen the number of layers is fixed, those local minima with less total optical thickness appear to be better.2. A detailed study is made to the realization of Needle method. Using the results thus got, a ED FA gam flattening filter is design from the starting structure of 2 layers whose error is within ?.1dB.3. Suggestion of the synthesis of narrow bandpass filters used in WDM by adding mirror and spacers. By adjusting the reflectance of every mirror and the...
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