| 摘要 |
PROBLEM TO BE SOLVED: To realize a quantum cascade laser oscillating in the far-infrared region or the terahertz region; particularly to realize a large gain by providing a basic structure for injecting/extracting carriers in a laser active layer with efficiency; and furthermore to realize a low threshold value, a continuous oscillating operation, and a high temperature operation by preventing thermal backfilling of carriers. SOLUTION: An active layer having a laser level of a four level system is composed of a carrier injection layer, a gain layer, and a carrier extraction layer; and population inversion is improved by using layers with higher-speed relaxation than the gain layer as the carrier injection layer and the carrier extraction layer. The high-speed relaxation in the layers is mainly relaxation by making relaxation level differences in the carrier extraction layer and levels of optical phonon uniform, or relaxation by causing stimulated emission with a laser from the outside. COPYRIGHT: (C)2008,JPO&INPIT
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