| 摘要 |
PURPOSE:To make possible selective excitation of one or a small number of higher modes by using a transparent double refracting plate and an optical fiber. CONSTITUTION:A double refracting plate 90 which is quadrisected and in which the axes of double refraction are so selected that the respective portions give rotation of lineary polarized light of 0, pi/2, pi, 3pi/2, is prepared. The double refracting plate 90 is then disposed as a double refracting plate 100 at the end face of an optical fiber 120 which propagates lihgt. With this arrangement, the incident light 130 focused by a lens 110 is separated to two modes by the double refracting plate 100 and propagated in the optical fiber 120. Here, if the polarizing rotation angles 0, pi/2, pi, 3pi/2 of the double refracting plate 90 are arrayed reversely, the two modes spacially rotated 45 deg. are excited. |
