| 摘要 |
PURPOSE:To realize decreasing the number of components of an optical amplifier and simplification of its constitution, to increase a gain by reciprocating amplifications of a signal light and to reduce noise. CONSTITUTION:The optical amplifier comprises an optical circulator 1, a rare earth element-doped optical waveguide 2, a wavelength selecting optical filter 3 and an exciting light source 4. The filter 3 passes an exciting light, and reflects a signal light. Thus, an output light of the source 4 is injected to the waveguide 2 through the filter 3 to excite the waveguide 2. The signal light input from the circulator side is amplified in the waveguide 2, then reflected by the filter 3, again amplified in the waveguide 2, and output from a port 12 of the circulator. Accordingly, an optical coupler for inputting the exciting light is eliminated to simplify the device, and the optical amplifier having a small spontaneous emission light noise and high gain can be realized. |
