High-power InAlGaAs laser diodes with high efficiency at 980 nm

Abstract

Within the last few years, high power laser diodes with remarkable improvements concerning output power, efficiency, and reliability have been investigated in the wavelength range between 780 nm and 1064 nm. The discussion, whether laser diodes fabricated from Al-free material systems can surpass the performance of devices made from the conventional InAlGaAs-material system is still ongoing. In our contribution to this discussion we present 980 nm high-power InAlGaAs-laser diodes and laser diode bars with high conversion efficiencies grown by MBE. Broad area laser diodes with 100 micrometer aperture show an output power as high as 9.2 W cw at room temperature corresponding to a COMD level of 17 MW/cm2. Up to this output power the conversion efficiency remains above 46%. The highest efficiency of nearly 60% is reached at 2.5 W of output power. Reliability tests are ongoing and predict a lifetime of at least 20.000 h at a power level of 1.5 W cw. Laser diode bars of 1 cm width comprising 25 of these oscillators have been fabricated. Similar to single emitters these devices achieve a conversion efficiency of 58% at 62 W of cw output power. In terms of conversion efficiency and output power these results are among the best reported for both, Al-containing and Al-free laser diodes and laser diode bars. They can be attributed to the material quality, the facet coating technology, and the design of our devices. Clearly, they show the competitiveness of the material system used here.