| 摘要 |
PURPOSE:To make it possible to control the optical output level of an optical relay on a light transmitting path by setting the magnitude of a pulse current base on the magnitude of a supplied current, setting the level of the light signal outputted from a laser diode, changing the supplied current, and adaptively changing the level of the light output from the laser diode. CONSTITUTION:The magnitude of a supplied current Ia flowing through a feeder line is detected with a current detector 1. A laser-diode driving circuit 3 is controlled with a detected voltage value Vb. Therefore, when an input signal (s) is inputted into the laser-diode driving circuit 3, the magnitude of a pulse current Ic is adjusted, and a light signal at a light output level corresponding to the magnitude of the supplied current Ia flowing through the feeder line is outputted. At this time, the pulse current Ic is further applied into a laser diode 5 in which a bias current Ib indicating a threshold current value has been already supplied. Thus the light signal at the light output level corresponding to the magnitude of the pulse current is outputted. In this way, the level of the light output from a terminal through an optical relay can be adjusted to the optimum level without newly providing a control line. |
