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Study On Polarization Characteristics And Optimization Designs Of Narrowband Filters Used In Tilted Incidence

Posted on:2006-08-19Degree:MasterType:Thesis
Country:ChinaCandidate:C WangFull Text:PDF
GTID:2132360155955323Subject:Communication and Information System
Abstract/Summary:PDF Full Text Request
Thin-film narrowband filters are applied to many fields. With the advancement of DWDM (dense wavelength division multiplexing) technologies, key parts of DWDM apparatus have been greatly developed. Fabry-Perot thin film filters, regarded as multiplex/demultiplex components, have been used extensively. Efficient optical thickness of thin-film at nonnormal incidence will decrease and central wavelength will shift in shortwave direction .Based on characteristic-matrix theory of thin-film optics, this paper gives some characteristics on multilayer filters used in tilted incidence. Characters of S-polarization and P-polarization will separate when the filter is in the incidence at nonzero angle .One is the central wavelengths of two polarization beams do not coincide with each other. The other is that passband width of S-polarization is less than that of P-polarization.Angle-tuned filter's central wavelengths of two polarization beams can coincide by adjusting effective refractive index of spacer. Beginning with the analysis of phase relationship and by use of the characteristic matrix expression of films, this paper deduces two implicit function expressions comprising moderate refractive index of spacer and central wavelength of P-polarization & S-polarization. Therefore the values of moderate refractive index and corresponding central wavelength can be quickly and accurately obtained.Similarly, this paper also deduces two function expressions comprising several key parameters by use of characteristic matrix expression of films. When initial status is known, values of low refractive index and the parameter-m are given, the values of high refractive index and moderate refractive index of designed filters can be easily worked out. Ultimately, the problem of two polarization beams' character splitting in tilted incidence can be well resolved by use of designed filters.
Keywords/Search Tags:Narrowband filters, Tilted incidence, Polarization, Central wavelength, Passband width
PDF Full Text Request
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