Measurement of thermal expansion coefficient and biaxial modulus of DWDM filters using phase-shift Interferometer

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Dense-wavelength-division-multiplexing (DWDM) filter is a very sensitive component in wavelength shift. The temperature shift of central wavelength (TSCW) of filter is depended on the mechanical properties of the stress. In this paper, a modified Stoney's equation was applied to analyze the thermal stress of DWDM filters for the reason of the thickness ratio (thin film thickness/substrate thickness) larger than 1%. The phase-shift interferometer and TSCW were applied to measure and achieve the coefficient of thermal expansion (CTE), biaxial modulus, temperature optical coefficient, stress optical coefficient, and Poisson ratio of DWDM filter. Based on this method, we can obtain the CTE of DWDM filter 0.87pm/°C,the biaxial modulus 41 GPa, Poisson ratio 0.22, temperature optical coefficient 1.4×10 -5/°C, and stress optical coefficients -1.9×10 -12/Pa. To achieve zero TSCW for a DWDM filter, the CTE of the substrate should be 10.36ppm/°C.

Original languageEnglish
Title of host publicationAdvances in Optical Thin Films III
StatePublished - 2008
EventAdvances in Optical Thin Films III - Glasgow, United Kingdom
Duration: 2 Sep 20083 Sep 2008

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


ConferenceAdvances in Optical Thin Films III
Country/TerritoryUnited Kingdom


  • Biaxial modulus
  • Coefficient of thermal expansion (CTE)
  • Phase-shift interferometer
  • Temperature optical


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