| 摘要 |
PURPOSE:To obtain specific isolation at low cost by using one dielectric multilayered film filter and branching light by plural-time reflection in the filter. CONSTITUTION:Light having wavelenghs lambda1 and lambda2 propagating in an optical fiber 1a is converted by a lens 2a into a parallel beam, which is incident to a band-pass filter 3. Light having the wavelength lambda1 is transmitted through the band-pass filter 3 to enter an optical fiber 1b. Light having the wavelength lambda2 is reflected three times by the band-pass filter 3 and twice by a mirror 6 to enter an optical fiber 1c. In this case, light power of the wavelength lambda1 in the light incident to the optical fiber 1c is about 30dB smaller than light power of the wavelength lambda2. Thus, the number of times of reflection by the filter is increased to obtain the specific isolation, so an expensive filter is not necessary. |
