| 摘要 |
PURPOSE:To prevent an influence upon a distribution in propagation mode even if a distribution ratio is varied, by rotating a phase difference plate and thus adjusting the branching and coupling ratio of the quantity of light. CONSTITUTION:Emitted light from an optical fiber 1 is collimated by a lens 2 and then separated by a polarizing and separating element 8 into P-polarized light and S-polarized light; the P-polarized light is reflected to change in direction by 90 deg., and is then emitted. The S-polarized light changes in direction by 90 deg. through a reflecting mirror. Then, the P-polarized light and S-polarized light are both guided to a phase difference plate 10 to rotate their planes of linear polarization by 2theta. The P-polarized light changes in direction through a reflecting mirror 11. The P-polarized light and S-polarized light both having the planes of linear polarization rotated by 2theta are caused to illuminate a polarizing and separating element 12, thereby obtaining the quantity cos<2>2theta of light at one end surface of an optical fiber 6 and the quantity 1-cos<2>2theta of light at one end surface of an optical fiber 7. Then, theta is varied by rotating the phase difference plate to vary the distribution ratio. |
