| 摘要 |
A Raman amplifier using at least three excitation frequencies, wherein, when excitation wavelengths are divided into groups of excitation wavelengths on a short wavelength side and a long wavelength side with an excitation waveleng th having the widest interval between adjacent wavelengths used as a boundary, a group on the short wavelength side contains at least two excitation wavelengths with almost equal wavelength intervals, and a group on the long wavelength side comprises up to two excitation wavelengths. When a certain excitation wavelength is defined as a first channel and second to n-th channels located from there toward the long wavelength side at about 1THs intervals are defined, excitation lights with wavelengths corresponding to t he first to n-th channels are multiplexed and then further multiplexed with an excitation light having a wavelength at least 2THz away from the n-th channe l toward the long wavelength side, for use as an excitation light source. Excitation lights having wavelengths corresponding to channels other than (n - 1)-th and (n-2)-th channels are multiplexed for use as an excitation light source. Excitation lights having wavelengths corresponding to channels other than (n-2)-th and (n-3)-th channels are multiplexed for use as an excitation light source. |
