Patent ID: 7043112

Claim:
An optical wavelength-multiplexing transmission system for transmitting first wavelength-multiplexing light and second wavelength-multiplexing light in opposite directions through an optical transmission medium allowing bidirectional wavelength-multiplexing transmission, wherein a wavelength band of the first wavelength-multiplexing light is set to a shorter wavelength side as compared to a wavelength band of the second wavelength-multiplexing light, said first wavelength-multiplexing light and said second wavelength-multiplexing light being simultaneously transmitted through said optical transmission medium and causing increased attenuation of the energy of said first wavelength-multiplexing light and reduced attenuation of the energy of the second multiplexing light, and excitation light having a wavelength shorter than the wavelength band of the first wavelength-multiplexing light travels through the optical transmission medium in a same direction as the second wavelength-multiplexing light and in a direction opposite to said first wavelength-multiplexing light, whereby said increased attenuation of said energy of said first wavelength-multiplexing light is compensated along the optical transmission medium.