| 摘要 |
PURPOSE:To decrease the number of interference filters, and also to simplify its arrangement without increasing the number of times of a reflection, by constituting the titled demultiplexer of a long wavelength filter, and the first band-pass filter and the second band-pass filter which have been placed on both its sides, respectively. CONSTITUTION:As for the light having plural wavelengths lambdaa-lambdad, which has been made incident on an optical fiber 16, the wavelengths lambdaa and lambdab pass through by a long wavelength pass filter 24, and other wavelengths lambdac and lambdad are reflected. As for the wavelengths lambdaa, lambdab which have passed through the filter 24, only lambdab is reflected by the first band-pass filter 26, the wavelength lambdaa is obtained from an optical fiber 20A, and the wavelength lambdab is obtained from an optical fiber 20B. On the other hand, as for the wavelengths lambdac and lambdad which have been reflected by the filter 24, only the wavelength lambdad is reflected by the second band-pass filter 28, and the wavelengths lambdac and lambdad are obtained from an optical fiber 20C and 20D, respectively. In this way, plural wavelengths can be separated by a small number of interference filters, and also the number of times of a reflection is reduced and the reflection loss is also reduced. |
