Thermal management in GaAs/AlGaAs laser diode structures

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Due to the advancement of nanotechnology, understanding the heat transport mechanism in nano-scale devices has become a crucial factor in describing the operation of the device. Laser diode structures have been the backbone for optoelectronic systems over the years. They are widely being used in state of art communication systems. Laser diodes are also used in defense applications as target defining device and in commercial applications as barcode readers and optical storage devices. However, thermal characteristics have been a deterring factor for their greater use. Hence, investigating thermal management in laser diode structures becomes an important and interesting study for current and future laser applications. In this research, thermal characteristics of laser diode structures were studied in detail. Factors such as thermal resistance and facet temperature, which affect the thermal properties of a laser diode structure, were analyzed in depth. Catastrophic optical damage (COD), which is a failure mode in a semiconductor laser due to high of power densities, was discussed in depth. In order, to understand the heat flow, a laser diode structure was modeled using Coventorware. Heat flux profiles extracted from the model clearly show that active region was fastest to get heated up as the absorption takes place in this region. Temperature profiles also show that the top surface of the laser diode structure reaches 800oK which is one of the main reasons for COD in laser diode structures. This model could be further implemented with different material properties to study laser diodes emitting different wavelengths. Moreover, the model can also be modified to study the thermal properties in a quantum cascade laser diode which is one of the active areas of research. Cooling mechanisms such as heat sink and heat spreaders can also be integrated in the design to improve the thermal properties of a laser diode structure.