| 摘要 |
PROBLEM TO BE SOLVED: To provide a material usable for optical communication and an optical integrated circuit board and having small temperature dependence of an optical path length.SOLUTION: A composite oxide material in which CaSnOis added to SrTiOcan control a temperature coefficient of an optical path length (OPD, where OPD=1/S×dS/dT=CTE+1/n×dn/dT, S represents an optical path length, CTE represents a linear thermal expansion coefficient, n represents a refractive index, and dn/dT represents a temperature coefficient of the refractive index); has a very small temperature dependence of the optical path length having an absolute value of 6 ppm/°C or less, especially, in a range of 0≤x≤0.75 and 0≤y≤0.5; and is available to an optical communication filter and an optical integrated circuit board and the like. |
