| 摘要 |
PURPOSE:To exceedingly reduce a coherency and to obtain the sufficient stability to the return light by enlarging a width of oscillation spectrum by sandwiching the central active layer with the outer active layers having a refractive index slightly different from that of said central active layer. CONSTITUTION:Among the active layers 4-6, the central active layer 6 has a P-type impurity concentration which makes the refractive index larger than the outer active layers 4 and 6 by the 10<-3> level. In the semiconductor laser of VSIS structure comprising such active layers 4-6, it can be recognized that the distribution of light intensity on a resonance surface oscillates within the distribution of a light emission region R by decomposing the light into spectra and measuring the light intensity. The laser thus obtained has a spectrum of 100GHz width and the exceeding reduction of coherency is attained and the extreme stability to the return light is obtained.
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