| Summary: | 碩士 === 國立彰化師範大學 === 光電科技研究所 === 93 === DVD related products have been appeared on the market since the late 20th century. Red AlGaInP laser diodes（LDs）with higher output power and efficiency are strongly required for the DVD-R/RW drivers, especially for improving the writing speed. According to the experimental results, the recording speed is proportional to the square of the output power of AlGaInP LDs. Therefore, to further improve the recording speed of DVD-R/RW, the output power of AlGaInP LDs has to be increased dramatically.
The purpose of this thesis is to investigate the performance of the high power 650-nm AlGaInP LDs with the consideration of thermal model. By taking the thermal effect into account, different laser diodes structures will cause different lattice temperatures, which in terms affect the output power of the AlGaInP LDs. In order to further increase the output power for the AlGaInP LDs, two key parameters, e.g. the cladding layer thickness and cavity length, are used for study. The theoretical analysis is done utilizing LASTIP simulation software plus the thermal model package.
In chapter one, the material characteristics and the development history of the AlGaInP LD will be first reviewed. Several methods used to improve the output power of the AlGaInP LDs will then be described. In chapter two, the influence of heat, induced inside the LD, on the performance of high-power AlGaInP LDs will be also illustrated. Different heat sources produced inside the AlGaInP LDs will be explained in great details.
In chaper three, the two-dimensional AlGaInP LD structure and the related thermal parameters used for simulation will be described first. The motivation to investigate the effect of the cladding layer thickness and the cavity lengths on the output power of AlGaInP LDs will also be explained. According to the simulation results, with the increase of cladding layer thickness, the absorption loss, resulted from the absorption of the optical fields in the GaAs contact layer and substrate, was decreased and the slope efficiency was thus improved. However, a very thick AlGaInP cladding layer will cause the heat dissipation problem for the AlGaInP LDs due to smaller thermal conductivity of the AlGaInP materials. Therefore, there should be an optimized thickness for the AlGaInP cladding layers. By taking the thermal effect into account, it is found that the optimized cladding layer thickness is about 1.7∼1.9 μm due to lower lattice temperatures and thus a better output performance can be achieved.
On the other hand, with the increasing of the cavity length, the operation current density can be further decreased. Therefore, the lattice temperatures of the devices can be reduced too and the output performance can be further improved. However, due to increase in the total heat, the cavity length can’t be increased without limitation. The final decision will base on the heat dissipation capability of the devices and the expected operation current.
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