| 摘要 |
PURPOSE:To remove the necessity of the changeover of light passes and reduce measuring procedures by changing the light output level of a variable light attenuator and measuring its input-output characteristics. CONSTITUTION:A circuit is composed of a light source 1 for outputting light signals of rectangular wave, a light source 2 for outputting continuous wave, a variable light attenuator 3, a light directional coupler 4 and the like. The levels of the light sources 1 and 2 are set, for example, to the degrees of -40dBm and 0dBm, respectively. The attenuator 3 of the degree of 40dBm is used and its output is made to the degree of 0dBm--40dBm. The light signals of continuous wave are inputted to the attenuator 3 and its light output and the light signals of continuous wave are inputted to the coupler 4. Its output is incident upon a light detector 5 to be measured. A rectangular wave component is measured from the output of the light detector 5 by an output measuring instrument 6 and the linearity of the light detector 5 is measured from change in the rectangular wave component. Accordingly, the changeover of light passes is made unnecessary, resulting in the reduction of measuring procedures.
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