| 摘要 |
PROBLEM TO BE SOLVED: To regulate the pumping level of a pumping light source automatically by providing first and second means for controlling the pumping level of pumping light outputted from first and second pumping light sources depending on the difference of level of optical signals being received at first and second terminal stations. SOLUTION: A received signal light S1 is demultiplexed and the signal level at a terminal station is determined at a level determining section 224 based on a demultiplexed signal S2. Receiving level information thus obtained is then converted through an A/D converter 225 into a digital signal which is inputted to a comparison control section 226. The signal light S1 is converted through an opto-electronic converting section O/E 227 into an electric signal which is inputted to an FEC decoder 228 at a receiving section. The FEC decoder 228 extracts the receiving level information of the signal light S1 and delivers it to the comparison control section 226 where the pumping level of a pumping light source 231 is elevated. According to the arrangement, pumping level of a pumping light source can be regulated automatically. |
