Calculation of the Gain and Absorption Coefficient in Quantum We- ll and Estimating the Efficiency for Reducing Carriers Current by Multiple Quantum Barriers in Semiconductor Lasers

• Main Authors: Kuo-Feng Chen, 陳國峰
• Other Authors: Wei Hsin
• Format: Others
• Language: en_US
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/86514418157652798602

碩士 === 國立交通大學 === 光電(科學)研究所 === 83 === First, the optical gain and absorption without Coulomb interacti- on between electrons and holes are analyzed for quantum well las- ers. When the intraband relaxation is considered, the gain/absor- ption spectral shape becomes smooth and broad in spite of the sh- arp step-like density of state. However, the Coulomb attraction between the conduction-band electron and the valence-band hole l- eads to considerable changes in the optical properties of the qu- antum well around the absorption edge, especially below absorpti- on edge. There are intense absorption lines below the bandgap en- ergy, that is, less photon energy is required for the exciton tr- ansition compared with the bandgap transition. Finally, we have provided a clear and simple method for the optimal design of any MQB structure by calculating the carrier blocking efficiency for the first time. Our method predicted substantial improvement of the differential quantum efficiency of a SCH-SQW laser with opti- mal MQB design and agrees with experimental results.