| 摘要 |
<p>PURPOSE:To increase a wavelength band and to decrease an output saturation by forming an active layer of a well layer having small band gap and a barrier layer having large band gap, and setting the thickness of the well layer to de Broglie wavelength or less of electron. CONSTITUTION:An active layer for amplifying a light is formed in a multiplex quantum well structure, and a plurality of barrier layers 4 each having large band gap and a plurality of well layers each having small band gap are alternately laminated. When the thickness of the layer 3 is reduced to de Broglie wavelength or less of electron, electrons in the well layer are enclosed in a two-dimensional manner. Accordingly, the energy distribution of the electron is narrowed, and a high gain is obtained in a low current concentration. Thus, the operating current density of an optical amplifier can be reduced. Further, when an N-type impurity is implanted to the well layer or the barrier layer, a wavelength band for obtaining a gain is widened, and since the slope of the gain-current characteristic is small, the saturation of the gain is small even with a strong incident light.</p> |
