| 摘要 |
PURPOSE:To obtain a doped fiber, and a gain monitor employing it, in which emission of pumping light can be interrupted without requiring any special means for removing the leakage pumping light. CONSTITUTION:One example of a doped fiber, i.e., an erbium doped fiber 31, is constituted of a core 32, a clad 33, and a coating 34 applied thereabout. The coating 34 is composed of a polymer material absorbing the light of 1480nm band which is equal to the wavelength of pumping light and transmitting the light of 1550nm band which is equal to the wavelength of signal light. Consequently, the pumping light does not leak to the outside of the erbium doped fiber 31. This erbium doped fiber 31 can constitute a highly accurate gain monitor without requiring any special filter. |
