Mid-infrared vertical cavity surface emitting lasers based on the lead salt compounds

Abstract

In conclusion, lead salt vertical-cavity surface-emitting lasers offer attractive properties as coherent infrared laser sources. In particular, they feature single mode operation, emit circularly shaped parallel beams with extremely small beam divergence, and exhibit very sharp emission lines widths below 12 μeV. Based on the use of high finesse infrared microcavity structures, pulsed mode operation has been achieved well above room temperature as well as CW-operation up to 120 K, which is expected to be significantly increased in the near future. In comparison with quantum cascade lasers, the lead salt VCSELs show a substantially larger wavelength tunability, which is of crucial importance for spectroscopy applications. In addition, lead salt VCSELs can be grown on readily available substrate materials. This not only drastically reduces costs and facilitates the laser fabrication, but also offers improved heat dissipation due to the higher substrate thermal conductivity. Up to now, lead salt VCSELs have operated only under optical excitation but with some technological efforts electrically pumped lasers should also become feasible. Alternatively, one can envision hybrid structures in which low cost and readily available NIR pump lasers are integrated in one package with the lead salt VCSELs to obtain easy to use and cost-efficient mid-infrared laser sources. This would certainly open many promising applications in a variety of different fields. © 2006 Springer-Verlag London Limited.