Thermal resistance measurement of edge-emitting semiconductor lasers using spontaneous emission spectra

An improved technique for thermal resistance measurement of edge-emitting diode lasers using spontaneous emission spectra, collected through the opening in the $n$-contact within the range of operating currents, has been proposed. The advantage of the proposed technique is that systematic errors typical for measurements based on lasing spectra are excluded. The accuracy of the method was verified by measuring the dependence of the thermal resistance on the cavity length for diode lasers with 100 $\mu$m strip width. Obtained results are in good agreement with the model, and the minimum measurement error was $\pm$0.1 K/W. The proposed technique can be used in metrological support of fabrication process of semiconductor lasers.