| 摘要 |
PURPOSE: To avoid the deterioration phenomenon of transmission quality connected with a Brillouin effect by providing a means for increasing the modulating speed of an optical carrier wave from a zero value as necessary when modulation is the one other than the intensity modulation. CONSTITUTION: In an optical transmission system including a transmission terminal equipment 1, optical link 2, and receiving terminal equipment 3 a comparator 10 compares the number of the valid carrier waves of an incident multiplex counted by a scanner 9 with a prescribed limit value. Then, when the number of the valid carrier waves of the incident multiplex is detected as less than the prescribed limit value, a control instruction is made active, and the gain of an adjustable gain amplifier 11 is increased and/or an auxiliary carrier wave is added through an auxiliary carrier wave generator 12 and a multiplexer 13. Thus, when a strong transmission light power is connected, reflection is generated inside the fiber of an optical link 2, and as a result, a phenomenon in which additional attenuation, deformation, and disturbance is introduced to a transmitted signal can be avoided or limited. |
