| 摘要 |
PURPOSE:To prevent even an optical signal with multi channel from being affected by image interference. CONSTITUTION:This device is constituted so that after the optical signal with a carrier frequency fa is intensity-modulated by an external modulation frequency fi, is converted to an electric signal, so that the relations among the carrier frequency fa, the external modulation frequency fi and a frequency ft after frequency conversion satisfy the expressions ft/3<fi<7ft/15, 5ft<fa<29ft/15. Further, the bias point of an optical external modulator 1 is selected to a point where the linearity of a modulation characteristic is large. Further, the bias point is selected to the point with large linearity so that the relations among fa, fi, ft satisfy the expressions ft/3<fi<15, 5ft/3<fa<29ft/15 or 4ft/7<fi<6ft/7, 11ft/7<fa<13ft/7. |
