| 摘要 |
PURPOSE: To lengthen the life of an element, by separating periodic absorption structure from an active layer to such a degree that the periodic absorption structure is not absorption-saturated, and setting the thickness to such a degree that a sufficient gain coupling constant is obtained. CONSTITUTION: The average light density in a light absorption layer can be controlled by adjusting the thickness of a carrier barrier layer 204, and the light density becomes lower than or equal to 6.0×10<3> cm<-1> when the thickness is 0.24μm or greater. The distance between an active layer 203 and a light absorption layer 206 is 0.3μm and sufficiently larger which is the sum of 0.25μm of the thickness of the carrier barrier layer 204 and 0.05μm of the thickness of a guide layer 205. The light density in the absorption layer 206 is 5.6×10<3> cm<-1> and sufficiently small. Thereby the switching of optical output- current characteristics which is generated by saturable absorption of the absorption layer 206 is not seen until the optical output is 50mW or larger, and stable single axis mode oscillation can be obtained. Since the crystal regrowth interface is distant from the active layer, a long life element can be realized.
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