| 摘要 |
PURPOSE:To amplify a light with a high accuracy and comparatively simple constitution by providing a beam splitter branching the output light of an electrooptic conversion means, applying a part to the 1st optical frequency conversion means and converting the remaining light into an output light in response to the quantity of an input light fed to the 2nd optical frequency conversion means. CONSTITUTION:The static capacitance of the depletion layer of a photodiode PD constituting optical frequency conversion means 1, 2 is increased as the quantity of input light is increased and oscillated frequencies f1, f2 are lowered as the static capacitance increases. The output signal of the optical frequency conversion means 1, 2 is fed to an up-down counter 3, where the difference of the frequencies f1, f2 is counted and outputted. A drive circuit 4 drives a light emitting diode 5 in response to the count output and its light emitting intensity is changed in proportion to the polarity and the amplitude of the count output. Since a part of the output light of the light emitting diode 5 is fed to the junction of the photo diode PD constituting the 1st optical frequency conversion means 1 via a beam splitter 6, the diode is in drive control to have the relation of f1=f2 and the input light IN is amplified in response to the transmitted light to the reflected light of the beam splitter 6. |
