Investigation of thermomechanical stress characteristics in high-power 808-nm AlGaAs/GaAs laser diode bars

The thermomechanical stress characteristics in high-power 808-nm AlGaAs/GaAs laser diode bars were investigated experimentally and theoretically using infrared thermography and finite element method in detail. The transient thermomechanical stress curves changing with total operation current were measured using infrared thermography. The results indicated that thermomechanical stress of laser diodes chip has a logarithmical dependence on the total operation current. In addition, the dependence of thermomechanical stress on total operation current was analyzed based on finite element method which was great consistent with the experimental results. The calculated results showed that thermomechanical stress of laser diodes chip had a higher increasing rate with higher operation current density, and the plastic deformation would occur when the thermal stress reaches the yield strength.