| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a gain equalizer which can properly flatten the gain spectrum of an optical amplifier by reduction of shift in the center wavelength caused by the temperature change to have the reproducibility and the mass productivity improved and to provide the gain equalizer which can give a large refractive index difference between two alternately laminated dielectric thin films different by refractive indexes and can reduce the number of layers of both dielectric thin films. <P>SOLUTION: A gain equalizer 31 is provided with a minus filter which is formed on one face of a transparent substrate 33 and is constituted of a dielectric multi-layered film filter 34 having first and second dielectric thin films different by refractive indexes alternately laminated. The minus filter is so constituted that a tertiary reflection band may appear in the position of a peak wavelength λ<SB>0</SB>of the gain spectrum, and the reflection band is utilized to flatten the gain spectrum. A large refractive index difference can be given between both dielectric thin films, and the number of laminated layers of both thin films is reduced. <P>COPYRIGHT: (C)2003,JPO |
