| 摘要 |
PROBLEM TO BE SOLVED: To provide a wavelength filter, overcoming the performance limit of a conventional flat multi-coated wavelength filter regarding a remaining transmission rate due to the refractive index of a used coated film material and a transition wave band width between a transmission wavelength band and a cut-off wavelength band. SOLUTION: The wavelength filter consists of the structure having an alternative multi-coated film structure made of materials having a different refractive index in z-direction in a three-dimensional space xyz, and in which the refractive index periodically varies with a period p in the x-direction, and periodically varies with a period q (q≥p) in the y-direction, while satisfying the relations p≤λ<SB>0</SB>and q>(λ<SB>0</SB>/3), whereinλ<SB>0</SB>is the wavelength of light made incident in parallel to the z-axis in vacuum. COPYRIGHT: (C)2009,JPO&INPIT |
