Effect of inter-level relaxation and cavity length on double-state lasing performance of quantum dot lasers
✍ Scribed by L.W. Shi; Y.H. Chen; B. Xu; Z.C. Wang; Z.G. Wang
- Book ID
- 104084700
- Publisher
- Elsevier Science
- Year
- 2007
- Tongue
- English
- Weight
- 230 KB
- Volume
- 39
- Category
- Article
- ISSN
- 1386-9477
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✦ Synopsis
Double-state lasing phenomena are easily observed in self-assembled quantum dot (QD) lasers. The effect of inter-level relaxation rate and cavity length on the double-state lasing performance of QD lasers is investigated on the basis of a rate equation model. Calculated results show that, for a certain cavity length, the ground state (GS) lasing threshold current increases almost linearly with the inter-level relaxation lifetime. However, as the relaxation rate becomes slower, the ratio of excited state (ES) lasing threshold current over the GS one decreases, showing an evident exponential behavior. A relatively feasible method to estimate the inter-level relaxation lifetime, which is difficult to measure directly, is provided. In addition, fast inter-level relaxation is favorable for the GS single-mode lasing, and leads to lower wetting layer (WL) carrier occupation probability and higher QD GS capture efficiency and external differential quantum efficiency. Besides, the double-state lasing effect strongly depends on the cavity length.