| 摘要 |
PURPOSE:To prevent a light to be coupled to an optical fiber from coupling to a specific mode and to realize a uniform inter-mode power distribution so that noises can be reduced, by installing an uneven part at the end face of an optical fiber into which light coming from a semiconductor laser is supplied. CONSTITUTION:Light coming out from the semiconductor laser 21 is converged by a rod lens with a spherical shape at the front end 22 and coupled to the optical fiber 23 through an oblique block 25. Since the concentric uneven part 26 is installed at the end face of the optical fiber 23 which is formed at right angles to the axis of the fiber 23 by etching, the light coming out from the laser 21 is scattered by the uneven part 26 and more uniformly coupled with each mode without being deflected to a lower mode of the optical fiber 23. Moreover, the inter-mode interference becomes hardly to occur and the ratio of speckle strength is suppressed lower than the case where the light is deflectedly coupled with a lower mode, and thus, mode noises are reduced. |
