| 摘要 |
PROBLEM TO BE SOLVED: To realize an optical equalizer which compensates the gain wavelength dependence of an optical amplifier and optical gain wavelength dependence and also has low loss polarization dependence. SOLUTION: Optical fibers 11 and 12 are optically connected through collimated beams by lenses 21 and 22. N pieces of etalon filters 30 whose FSRs (free spectrum region) are mutually different are inserted between the lenses 21 and 22. The loss maximum, loss minimum and FSR of the N-th etalon filter are set by performing Fourier series expansion of the gain wavelength characteristics of an optical amplifier applying an optical equalizer. Furthermore, as for an etalon filter, a filter obtained by forming a dielectric multilayer film having specific reflectance or a metal film on both faces of a glass plate, a filter obtained by forming a dielectric film on a glass plate with prescribed thickness by such as vacuum evaporation, etc., can be used. |
