Imaging thermography in the 3–5μm wavelength range is applied to the analysis of thermal properties of high-power diode lasers. We investigate these devices by inspecting their front facets as well as their active regions along the resonator. The latter is done through top windows within the substrate. Raw data are found to be mostly interfered by thermal radiation traveling through the substrate, which is transparent for infrared light. Substracting this contribution and recalibration allows for obtaining realistic temperature profiles along laser structures. Facet heating is analyzed complementary by micro-Raman spectroscopy. We show how hot spots at the front facet, in the substrate, or even in the active region within the substrate are discovered. Our approach paves the way for an advanced methodology of device screening.

The structural and electronic properties of the zinc-blende, p-Sn and rock-salt phases of BP are calculated within the local-density approximation. Two competing methods-LMTO and the pseudopotential plane-wave method-have been used. The agreement between the two electronic structure methods is excellent. We obtain the pressure versus volume equation of state and the pressure dependence of the structural and electronic parameters in good agreement with experiment and some previous calculations. Our calculations confirm that for BP crystal in the zinc-blende phase there is an indirect gap (of approximately 1.5 eV) which decreases quadratically with pressure and that the phase transition from zinc-blende to rock-salt phase occurs at extremely high pressure (approximately 150 GPa). We observe that BP crystal in the p-Sn phase is stable only at very high pressure.

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