| 摘要 |
PURPOSE: A one-staged optical pre-amplifier is provided to reduce a production unit cost and a circuit size, and allow an optical receiver to be operated in an optimum state. CONSTITUTION: An EDF(Erbium Doped Fiber) amplifier(31) amplifies an input optical signal with an input level of -10 to -26 dBm to an output level of about 0 dBm, and outputs the amplified optical signal. A DCFM(Dispersion Compensation Fiber Module)(32) compensates a dispersion value contained in the optical signal, and in this case, about 7 dBm of optical loss is generated. An output terminal(33) branches the optical signal outputted from the DCFM(32) and inputs them to an optical receiver and a circuit for an APC(Automatic Power Control). That is, an optical amplification degree of one amplifier is increased so high as to sufficiently amplify a signal. A final output optical strength is -7 dBm which is in the range of the optimum receiving light strength. Input of an optical signal with a signal level higher than 0 dBm to the DCFM would cause a nonlinearity for a DCFM output optical signal, so the optical strength of an output optical signal of the EDF output unit should not exceed 0 dBm.
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