| 摘要 |
In an optical amplifying device, an optical direct amplifier (11) amplifies input optical signals subjected to wavelength division multiplexing (WDM). An optical feedback is used, comprising a beam splitter (12) that splits the amplified WDM signals into two. An optical filter (13A) separates a particular optical signal from one of the two outputs of the beam splitter (12). An optoelectrical converter (14) converts the separated optical signal to a corresponding electric signal. A gain controller (15) controls the gain of the direct amplifier (11) on the basis of the electric signal output from the converter (14). The optical filter 13A may be replaced with an optical variable filter (13B) and controlled by control means when the optical signal for gain control is shut off or sharply varied in wavelength. Because the gain of the direct amplifier (14) is controlled by use of particular one of the plurality of WDM signals, the individual optical signal is controlled to a preselected level even when the number of WDM signals is changed. <IMAGE> |
