| 摘要 |
An optical transmitter is disclosed. The transmitter provides, in addition to a semiconductor laser diode as a light source, a variable polarizer with a Farady rotator and a polarization analyzer on an optical path of the laser diode. When the wavelength of the emitted light from the laser diode shifts, by adjusting the rotation angle of the Farady rotator by the current supplied to the coil so as to align the rotation angle with the polarization plane of the polarization analyzer, the wavelength shift of the laser diode may be estimated. Also, by comparing the optical magnitude between the initial of the operation and after the long-time operation at the output from the polarization analyzer after the alignment of the rotation angle of the Farady rotator, the degradation of the laser diode is detected.
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