Improved characteristics of bottom-emitting, oxide-confined, polyimide-wrapped VCSELs

Bottom-emitting, 980-nm vertical-cavity surface-emitting lasers flip-chip bonded on copper- and indium- plated heat spreaders were fabricated and characterized. Flip-chip bonding bottom-emitting VCSELs reduced the devices´ thermal resistance by 35% and increased the bias current density at which the maximum output optical power achieved by 19%, which increased the maximum output optical power achieved by 26%. Bonded VCSELs with oxide aperture diameters of 20-μm exhibited about 34°C decrease in active region temperature. Bonded and unbonded devices with different oxide aperture diameters demonstrated a threshold current density and slope efficiency of ~ 0.9kA/cm² and 0.72W/A, respectively.