| 摘要 |
PURPOSE:To obtain an optical signal with low distortion even when the signal is transmitted through an optical fiber for a long distance, 45 using one light emitting element and an optical modulator to cancel distortion of the optical signal. CONSTITUTION:In the case that an amplification factor of an amplifier 7 and a phase of a phase shifter 8 so that the amplitude of an output signal of the amplifier 7 received by a coupler 9 and that of an output signal of the phase shifter 8 are equal to each other and the phase of the output signal of the amplifier 7 received by the coupler 9 and that of the output signal of the phase shifter 8 are opposite o each other, when distortion takes place due to nonlinearity of a light emitting element 4, only the distortion generated by the light emitting element 4 is outputted to an output of the coupler 9. Thus, an optical modulator 16 applies a distortion signal to the optical signal propagated through the optical fiber 5. When the drive level of an optical modulator drive section 15 and a length of the optical fiber 5 are set so that the amplitude of the distortion signal in the optical signal propagated through the optical fiber 5 and the amplitude of the distortion signal modulated by the optical modulator 16 are equal to each other and the phases of them are opposite to each other, then the distortion signal in the optical signal propagated through the optical fiber 5 is cancelled by the distortion signal modulated by the optical modulator 16 and only the optical signal is outputted from an optical output terminal 14. |
