| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To make excitation light unpolarized in order to reduce the dependence of polarized wave on a Raman gain. <P>SOLUTION: In an unpolarized excitation light source 5, the output light of a laser light source 1 is substantially linear polarized light having a plurality of mode components spaces at almost the same intervals of angular frequencies. The output light of the laser light source 1 is coupled with a polarized wave dispersion device 3 so that the angle between the polarized wave axis and that of the polarized wave dispersion device 3 is substantially 45 degrees. the polarized wave dispersion device 3 provides incident light from the laser light source with an amount of polarized wave dispersion quantity that avoids the vicinity of 2π/Δω, whereΔωdenotes the mode interval of angular frequency. As a result, although the optical path difference between polarized wave modes is shorter than a coherent length, effectively unpolarized excitation light is outputted from the unpolarized excitation light source 5. Therefore, in an optical fiber 7 which is a Raman medium into which unpolarized excitation light is injected, the dependence of polarized wave on the Raman gain is reduced. <P>COPYRIGHT: (C)2003,JPO</p> |
