| 摘要 |
PURPOSE:To reduce the influence of optical fiber dispersion by providing an optical nonlinear element which generates a return spectral wave which shifts in frequency from a light signal and an optical fiber which cuts off the light signal component of its output light to be inputted to the nonlinear element and transmits the return spectral wave. CONSTITUTION:Transmission line dispersion is caused by a difference in transmission speed and when signal light 4 is inputted to a 1st transmission line 5 with dispersion, the light is affected by the transmission dispersion in the 1st transmission line 5 because of the spectral spread of the signal light 4. The return spectrum component of the signal light 6 which is affected by the transmission line dispersion is generated and when the light is further propagated in a 2nd transmission line 13 which has the same dispersion sign, the light is affected by the dispersion in the opposite direction, so the influence of the dispersion of the 1st transmission line 5 is canceled. Consequently, the dispersion can be compensated and the return spectrum component is extracted by using the optical filter and amplified by an optical amplifier to eliminate a drop in the light level, thereby suppressing both the loss and dispersion of the transmission lines. |
