| 摘要 |
PURPOSE:To reduce the length of a rare earth element or transition metal-added optical fiber by applying a reflecting mirror for reflecting only an exciting light to the output terminal of a rare earth element or transition metal-added optical fiber, and again introducing the light to the optical fiber by using the mirror. CONSTITUTION:An exciting light IP is reflected to the output end face of a rare earth element or transition metal-added optical fiber 1 of an active medium, and a reflecting mirror 4 for transmitting a signal light IS is added thereto. Thus, if the reflecting mirror 4 does not exist, the light IP to be externally discharged is again introduced into the fiber 1. Accordingly, the light is effectively absorbed into the fiber 1. In this manner, the fiber 1 can be shortened, and a photoamplifier can be reduced in size. |
