| 摘要 |
PURPOSE:To obtain a laser device which performs longitudinal multi-mode oscillation though it is refractive index waveguide type and to attain a stable operation without astigmatism and a noise even for a returned light by providing an active layer for performing laser oscillation and a light emitting layer for generating spontaneous emission light. CONSTITUTION:This device comprises a semiconductor substrate 1, first semiconductor layers 1, 2, 3 including at least an active layer 3 formed on the semiconductor substrate 1 and including a resonance structure for stimulated emission of light, second semiconductor layers 4, 5, 6, and 7 for spontaneous emission of light which are formed on the first semiconductor layers 1, 2, and 3 closely to the active layer 3. The spontaneous emission light generated from the second semiconductor layers 4, 5, 6, and 7 are injected into the first semiconductor layers 1, 2, and 3. Consequently, the spontaneous emission light of wide spectrum line width is injected into the active layer 3 so that a spontaneous emission light intensity in the active layer 3 increases. Thus, a semiconductor laser performs longitudinal multi-mode oscillation.
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