| 摘要 |
PURPOSE:To constitute the branch coupler so that a filter wavelength characteristic between each optical port is arranged at a roughly constant wavelength interval, plural wavelength can be classified by one piece of common filter, a loss of each optical port can be measured independently, and even in the case of a branch of a large scale, light propagated through each branch transmits through one piece of filter by each wavelength, and it is not influenced by a disturbance light. CONSTITUTION:In the branch coupler with a filter provided with at least one piece of optical port 6, an optical port group consisting of plural pieces of optical ports 71-78 allowed to branch or coupled from the optical port 6, and singular or plural common dielectric multi-layer film filters 8 provided so as to intersect with each optical port 71-78 of the optical port group, intersecting angles of the dielectric multi-layer film filter 8 and each optical port 71-78 are all different, and also, when an incident angle of the optical port in its intersecting point, and a specific refractive index difference of the optical port are denoted as alpha and DELTA, respectively, denotes an angle for satisfying sinalpha>=sq. rt. (2DELTA). |
