PURPOSE: To realize a low cost and miniaturization of an optical repeater, by branching the output of a semiconductor laser light amplifier to convert it into an electric signal and then controlling the intensity of an optical signal delivered from a laser medium with said electric signal to give an AGC function to an optical amplifier.
CONSTITUTION: An optical signal supplied to a laser medium 1 is amplified by the medium 1, and this amplified optical signal is delivered via a Y branching circuit 2. In this case, some beams are branched by the circuit 2. These branched beams are received by a pin photodiode 3 and then converted into electric signals proportional to the light intensity to be supplied to a gain control circuit 4. The circuit 4 supplies a DC current to the medium 1 in proportion to the intensity of the light which amplified the input electric signal. If the level of the output signal of the medium 1 is high, the current supplied to the medium 1 is increased by the output of the circuit 4. Then the amplification factor is reduced, and the gain is automatically controlled.
KIYOTA SHINJI
IFUKURO SADAO
| JPS56162554A | 1981-12-14 |
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