| 摘要 |
<p>A control circuit controls a directional-coupling type optical switch, inputs excited light from an excitation LD light source mainly via a WDM coupler to an EDF, and thereby intensifies forward excitation and controls drive current of the light source so that signal light with a desired value is output. On the other hand, when signal light power with a desired value is not obtained even when the drive current of the light source reaches an upper limit, the control circuit gradually increases the ratio of the excited light to be entered to the EDF via the WDM coupler, and at the same time controls the drive current of the light source so that the signal light with the desired value is output. <IMAGE></p> |
