Diode lasers emitting at 760 nm with high optical output power and high beam quality are in great demand. These III-V semiconductor light sources are also becoming increasingly popular since they do not only offer high beam characteristics but also very small dimensions. They are required for a wide range of applications including quantum photonics, sensors, and material analysis. In many cases, they need to be operated outside laboratories with limited space and in hazardous conditions; such as in space and for planets exploration. In this context, tapered laser diodes (TPL) are very promising candidates to fulfil these needs. They can reach very high optical powers with excellent beam qualities both as single emitters or in stacks, and can be assembled as laser modules with very small dimensions.
FBH has successfully developed novel 6-mm tapered laser diodes emitting at 760 nm. For this purpose, quantum well laser structures were grown by metalorganic vapor-phase epitaxy. After optimizing the epitaxial structure and the length of the ridge waveguide section, the lasers were mounted p-side up on conduction-cooled heat sinks for continuous-wave operation, which allows separate driving currents for the RW (IRW) and TA (ITA) sections.
The mounted lasers feature an optical output power of up to 9 W, a conversion efficiency of more than 50 % at heat-sink temperatures of 15 °C and a nearly diffraction-limited beam. Furthermore, the beam at 4 W optical power offers with 70 % a significantly high percentage of power at the central lobe. These results are a significant breakthrough compared to other available TPL at this wavelength, as the maximum optical power so far was limited to 1.5 W.