| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical system proper to a high speed response performance in which stability for a long term for a wavelength demultiplexed/ multiplexed signal is ensured by detecting the spectrum of a signal light using a monitor, dispersing, photo-electrically converting and making arithmetic operation. SOLUTION: A monitor signal light emitted from a stimulation termination of an optical fiber 2 is collimated by a lens 4 and the result is fed to a reflection diffraction grating 6. A light receiving element array 10 uses photoelectric conversion elements 12 to measure a dispersion from the diffraction grating 6. The direction of arrangement of the photoelectric conversion elements 12 is selected in parallel with this paper to allow the optical power of each wavelength to be measured by the array 10 altogether. An output signal from the array 10 is fed to a signal processing circuit 14. In this embodiment, a spectrum detected by an optical spectrum monitor 34 or monitor information based thereon is fed to a control circuit 36, the wavelength of a signal light of each channel is detected, based on the spectrum detected by the monitor and a laser diode 24 is controlled so that each wavelength is set constant. |
