| 摘要 |
PURPOSE: To totally reduce the degree of polarization of an optical signal and to suppress the PHB(polarization hole burning) by increasing the full polarization mode dispersion caused in an optical fiber transmission line compared with the reciprocal of the standard deviation of optical frequency spectrum of the optical signal to be transmitted. CONSTITUTION: Two inverted distribution of exciting density of an erbium atom can be suppressed when the polarization states are orthogonal to each other between two optical signals of wavelengths λ1 and λ2. Then the PHB can also be suppressed. This effect is limited only when the value of full PMD(polarization mode dispersion) of an optical transmission line is comparatively small. The optical transmitters 111 to 11n output the optical signals of linear polarization of wavelengths λ1 to λn in the same amplitude, then sent to an optical coupler 12 and coupled into a single signal. The output terminals of transmitters 111 to 11n are connected to the coupler 12, via a polarization holding fiber, and every optical signal is paired with another. These paired optical signals are adjusted so that their polarizing directions are orthogonal to each other. Thus the polarization state of coupled optical signals are turned during their transmission in response to the difference of frequency between them. Then a state equal to the polarization scramble is secured. |
