| 摘要 |
PURPOSE:To enable usage in a line service state and to unnecessitate a complicated bit operation by modulating the polarizing azimuth of the oscillating beam of a semiconductor laser by a supervisory control signal and demodulating this after transmission. CONSTITUTION:Corresponding to a supervisory control signal (a), an electromagnet 2 generates a magnetic field, the polarizing azimuth of the output beam from a semiconductor laser 1 is rotated at 90 deg., and an output beam (b) of a Faraday element 3 is obtained. This output beam (b) is transmitted by a polarizing face preserving filter 5 and later splitted into two directions by a beam splitter 6, one splitted beam is photoelectrically transduced by a photodetector 7, afterwards, a data signal is detected, the other beam is inputted to a polarizer 8 and only an output beam (c) is outputted. This output beam (c) is photoelectrically transduced by a photodetector 8 and afterwards, a frequency component (d) coincident with the signal (a) is detected by a band pass filter 10. Thus, the usage in the line service state is enabled, and the complicated bit operation is unnecessitated. |
