Transient Responses of Two-State Lasing and Optical Modulation in Quantum-Dot Lasers

• Main Authors: Sheng-Zhen Wu, 吳昇展
• Other Authors: 毛明華
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/51681131750942760115

碩士 === 國立臺灣大學 === 電子工程學研究所 === 95 === The phenomena of two-state lasing has been the popular research in the past few years. Before applying the characteristics of two-state lasing in quantum dot lasers into application fields, studies of the fundamental mechanisms are very important. By analyzing the behaviors of transient responses in two-state lasing, we observed the effects of homogeneous broadening strongly reduced the GS gain, and induced ultra-long relaxation time, and caused ultra-long turn- on delay. While the current pulse was turned off, the effect of homogeneous broadening was also removed. Therefore, we observed that GS turned on again which implied the homogeneous broadening effect deeply affected the GS during current injection process. By measuring the transient responses of the quantum dot laser pumped by a Ti:sapphire laser, the free carriers generated in the GaAs region absorbed the photons emitted from GS, and caused GS to stop lasing. We extracted a reasonable K-factor from the small signal modulation by optical excitation, which implied this kind of measurement is feasible.