| 摘要 |
PURPOSE:To make a stable optical input level value which is always in a stipulated range easily obtainable at each terminal device even if a terminal device or optical branching tap is increased or removed, by controlling a driving voltage by utilizing the variable characteristic of the branching ratio of the output optical power of an optical switch. CONSTITUTION:This optical signal branching device is provided with an optical switch 1 having one input and two outputs, optical level detecting means 2 which detects the optical level of one (b) of the two optical outputs, and branching ratio controlling means 3 which controls the level of input light to a terminal device to a set value in accordance with the output of the optical level detecting means 2. The optical level detecting means 2 converts the optical level of the one optical output (b) of the optical switch into electric signals and the branching ratio controlling means 3 controls the voltage to be applied across the branching electrode of the optical switch 1 so that a set optical branching ratio can be obtained to the optical power of a light source. Therefore, even if a new optical branching tap is increased or one tap is removed, the branching ratio can be controlled at every optical switch when the ratio set in the branching ratio controlling means 3 is reset. |
