| 摘要 |
PURPOSE:To eliminate the modal distribution noise by coupling two sets of semiconductor lasers optically and providing a saturable absorbing body onto an optical path between them so as to avoid the selection of the semiconductor lasers by their emitting wavelengths. CONSTITUTION:The titled device consists of the semiconductor laser 2, the saturable absorbing body 3 and the semiconductor laser 4. In applying direct modulation to the semiconductor laser 2 by a drive current 6 being the superimposition of a digital electric signal on a DC current, its optical output 5b is changed, e.g., as shown in figure and the power of an optical output is constant at each pulse. It is known that the spectrum of the laser optical output 5b at each pulse is changed at each time at random. Since the random optical power between spectrums eliminates the variation, the modal distribution noise is suppressed.
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