| 摘要 |
PURPOSE:To limit the effect of a reflected return light on a transmission characteristic to the least through a simple and cheap structure by a method wherein a polarization controller is interposed between the output end face of an optical fiber and a semiconductor laser. CONSTITUTION:A polarization controller 6 is inserted to a part of an optical fiber pig tail 2. That is, light rays projected from a semiconductor laser 1 are linearly polarized in general, and if the polarized wave front is horizontal, a part of the projected light is reflected by a connector 3 and reciprocated in the pig tail 2, so that the reflected light grows generally an elliptically polarized light and is fed back again to the semiconductor laser 1. But, the semiconductor laser 1 can be changed in characteristic through the reflected return light by converting the polarization of the reflected return light to a linearly polarized light vertical to the polarized wave front of the projected light through the polarization controller 6. By these processes, the adverse effect of a reflected return light on a light transmission characteristic can be restrained. |
