Improving The COD Level Of High-Power Semiconductor Lasers Using Quantum Well Intermixing

Due to the properties of high efficiency, high power, and high reliability, high power semiconductor lasers has received wide application in the fields of pumping solid lasers, communicating, material processing, printing, and medical treatment. Pursuing high power and high reliability was the main effort in the research of high power semiconductor lasers. The outstanding problem that limits the output power and reduce the reliability of the high power semiconductor lasers has been COD (Catastrophic Optical Damage) presenting at the device facet. Fabricating NAM (Non Absorbing Mirrors) was an important way to solve the COD problem. By using a QWI (Quantum Well Intermixing) process, NAMs could be easily fabricated with the advantages of low cost and high availability. In this article, theory analyses and experimental efforts were presented in investigating the characteristics of the QWI technology.The basically theories of COD and QWI were introduced first. The substantial mechanism of QWI was the compositional atoms interdiffusion between the barrier and well of the heterostructure via point defects, so theoretical interdiffusion model was presented based on analyzing the characters of point defects. Fermi level effect was emphasized in the process of QWI. Mechanisms of IID (Impurity Induced Disordering), IIID (Ion Implantation Induced Disordering) and IFVD (Impurity Free Vacancy Induced Disordering) were introduced, and properties of each method were discussed.Various processing parameters and their influence on QWI were investigated in the experiments. Results were analyzed using the theoretical model presented, and processing parameters were optimized. Finally selective area QWI met the requirement of NAM application was obtained. Differential wavelength blue shift more than 30 nm was achieved by QWI process, and COD level of the lasers was improved.