| 摘要 |
PURPOSE:To simplify the constitution of circuit to eliminate the need of a wide dynamic range by variably setting the quantity of attenuation of an input optical signal by a current-controlled optical attenuating element. CONSTITUTION:Input light from an optical fiber 1 is obtained as an optical reception circuit output V0 from an optical receiver 3 through an optical attenuating element 2, and in this case, a control voltage Vcont from the optical receiver 3 acts upon optical switches 9-11 as control currents IC1-IC3 through an A/D converter 4 to control the attenuation of the input light in the optical attenuating element 2. Thus, a wide dynamic range is not required in the optical receiver 3 and the circuit constitution is simplified. |
