Thermal Design of VCSEL Arrays for Optical Output Power Improvement

This study investigates the thermal design of 2-D vertical-cavity surface-emitting laser (VCSEL) arrays for optical output power improvement. Considering the temperature dependencies of bias current, internal quantum efficiency, internal optical loss, and thermal resistance of each array cell, a compact electro-opto-thermal model of 2-D VCSEL arrays with linear power dissipation and quadratic power dissipation in each array cell is established to study the effects of array cell spacing and layout on the device performance. At the same time, the power dissipation mechanisms contributing to thermal rollover are also studied. It is found that the array cell spacing has a strong influence on the linear power dissipation, and the layout (such as hexagonal design) influences quadratic power dissipation obviously. With the careful design of array cell spacing and layout, both the temperature profile and the thermal resistance matrix of VCSEL arrays are improved, which is helpful to delay the onset of thermal rollover and hence enhance the optical output power. The simulation results are consistent with experimental results.