| 摘要 |
PURPOSE:To transmit information such as alarm information, etc., collectively together with an optical main signal by a light direct amplifier. CONSTITUTION:The alarm information 28 is inputted to an alarm detection circuit 27, and a switch circuit 31 selects either a first oscillator 321 or a second oscillator in conformity with H or L of its digital signal. A first semiconductor laser drive circuit 241 drives a first semiconductor laser 211 by frequency f1 outputted from the first oscillator 321. A second semiconductor laser drive circuit 242 drives a second semiconductor laser 212 by the frequency f2 outputted from the second oscillator 322. Exciting light outputted from these is multiplexed by a photocoupler, and is injected from a wavelength dividing multiplex photocoupler 13 arranged behind an erbium added fiber 12. Thus, signal light which is the optical main signal modulated by the alarm information 28 is obtained from an output terminal 15. |
