Understanding and Predicting the Performance of Laser Diodes Under Irradiation

Optoelectronic devices such as laser diodes often find service in extreme conditions where their performance might degrade. Thus, understanding and predicting that performance becomes paramount. However, such devices are often very complex, precluding a fundamental understanding of their properties. Here, we undertake a research effort to both make and model a simple laser diode with the goal of developing a predictive capability of its performance under irradiation from first principles.<br/> <br/>We synthesize a simple GaAs laser diode structure and characterize the radiation-induced changes in structure and defect content, using microscopy to probe mesoscale changes in microstructure and electronic structure as well as a range of spectroscopies to examine the properties of the defective material. These properties are then correlating with changes in the overall lasing performance of the device.<br/> <br/>In parallel, we develop models of the same device structure, using density functional theory defect thermokinetics to develop a cluster dynamics model of damage that is then input into a device-level model. The device model predicts how those defects influence the light output and the lasing power of the device. These are compared to our experimental results to understand what defects are most responsible for any observed changes in the device performance seen in our experimental efforts.<br/> <br/>This effort provides new insight into how radiation-induced defects impact the performance of laser diodes and ultimately can lead to new strategies to mitigate those effects. In this talk, I will provide a summary of where we are in our efforts and the physical insights we have gained to date.