| 摘要 |
PURPOSE:To perform efficient branching and coupling between a bus fiber and tap fibers in the transmission line where plural optical couplers are coupled and to obtain equal output levels by setting parameters of optical fibers so that they are successively different by continuous optical couplers. CONSTITUTION:Two optical, fibers 211 to 213 and 211 to 213 different by parameters are connected in a welded part with respect to at least one optical fiber of each optical coupler, and the parameter 221 to 223 of one optical fiber out of two optical fibers different by parameters is different in each of continuous optical couplers. A proportion of coupling to the output tap is small in a first optical coupler 31 because the optical mower from a bus fiber 10 is higheset but the clad of the tap fiber 221 is thick. Meanwile, proportions of coupling are increased in succeeding optical couplers 32 and 33 because clads are made successively thin, and the optical power is efficiently obtained, and approximately equal outputs are obtained. |
