| 摘要 |
An optical transmitter according to the present invention stops the output of a signal light and transmits a dummy light, upon an occurrence of abnormality of the signal light output. If an abnormality detection circuit placed in the optical transmitter detects either a change in the power of the signal light or a change in the wavelength at least, a monitoring circuit stops the output of the signal light, and transmits a continuous light, which has the same power and wavelength as those of a normal signal light, as a dummy light. The dummy light is output just after an abnormality of a signal light has been detected. Otherwise, the dummy light is always transmitted, and it is output from the optical transmitter by changing over an optical switch. <IMAGE> |
