| 摘要 |
PURPOSE:To inhibit the deterioration of transfer characteristics by reflected return light by connecting the transmission path of excitation light to one input path of input signal light in the first and second directions and inputting excitation light to an optical fiber through first or second circulator. CONSTITUTION:The transmission path of excitation light is connected to one input paths L1F, L1B of input signal light in the first or second direction, and excitation light is input to an optical fiber FA, to which an active substance generating stimulated emission is added, through first or second circulators C1, C2. Consequently, even when excitation light is introduced to the optical fiber FA, light is amplified and reflected light is generated in a light transmission path, reflected light is suppressed, and intrusion to the optical fiber FA is prevented. Accordingly, the deterioration of transfer characteristics by reflected light is obviated. |
