| 摘要 |
PROBLEM TO BE SOLVED: To improve ripples in the transmission band generating according to the number of cavities. SOLUTION: The multicavity optical filter of a Fabry-Perot type dielectric multilayered film is prepared by stacking a plurality of basic units, each basic unit produced by alternately depositing high refractive index layers H and low refractive index layers L with the same optical film thickness as the reflective units on both sides of a cavity layer. In the above optical filter, one of the alternately laminated layers in each reflective unit is replaced by a symmetric or asymmetric three-layer film in which the high refractive index substance and the low refractive index substance both used for the above alternately laminated layers are alternately deposited with smaller pitches. Thus, the refractive index of the high refractive index layer H or the low refractive index layer L is varied to decrease the ripple.
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