| 摘要 |
PURPOSE:To suppress 4 light wave mixing regardless of the spectral line width of a light source by enabling the restriction of the number of multiplex channels of light frequency multiplex signals and restriction of channel intervals according to 4 light wave mixing and improvement in permissible fiber input levels. CONSTITUTION:A polarization controller 41-1 controls the output light of a semiconductor laser 1-1 to polarized light which repeats perpendicularly polarized light and horizontally polarized light. A polarizing separating section 43-1 separates the output polarized light of the polarization controller 41-1 branched by an 1X2 coupler 42-1 to the perpendicularly polarized light and the horizontally polarized light. Low-pass filters 46-1, 47-1 average the polarization levels of the perpendicularly polarized light and horizontally polarized light photoelectrically converted by opto-electric conversion circuits 44-1, 45-1 and output these levels to a control section 48-1. This control section 48-1 controls the perpendicularly polarized light and the horizontally polarized light in such a manner that both thereof are maximized and repeated in accordance with the polarization levels of the averaged perpendicularly polarized light and horizontally polarized light and the signal of an oscillator 2 delayed by a delaying circuit 3-1. |
