TEMPERATURE CHARACTERISTICS OF A VERTICAL-CAVITY SURFACE-EMITTING LASER WITH A BROAD-GAIN BANDWIDTH

Temperature-insensitive characteristics are of great importance in implementing the actual applications of vertical-cavity surface-emitting lasers (VCSEL's) because of the temperature change in the surroundings. To extend the operational temperature range of such lasers, we fabricated a VCSEL with a broad gain bandwidth. The active layers in VCSEL's consist of multiple quantum wells (MQW's) with different bandgap energies. From the change in the threshold current, with temperature as a parameter, we found that the operational temperature range of a VCSEL with a broad gain bandwidth is more than 20 degrees C wider than that of conventional VCSEL's, whose active layers consist of a single type of MQW. We demonstrate that the extended-gain bandwidth gives better temperature characteristics, In addition, we simulated the structure of the active layers, and the optimized structure resulted in a 1-mW light output power at less than 5 mA in a single transverse mode oscillation from 20-70 degrees C.