Journal of Thermal Analysis, Vol. 45 (1995) 417r436 ANALYSIS OF THERMAL BEHAVIOUR OF HIGH POWER SEMICONDUCIDR LASER ARRAYS BY MEANS OF THE FINITE ELEMENT METHOD (FEM) A. Bhrwolff, R. Puchert, P. Enders, U. Menzel and D. Ackermann Max-Born-lnstitut ffir Nichtlineare Optik und Kurzzeitspektroskopie, Rudower Chaussee 6, D-12489 Berlin, Germany (Received September 11, 1994) Abstract New results of steady-state two-dimensional finite-element computations of temperature dis- tributions of high power semiconductor laser arrays are presented. The influence of different thermal loads on the 2/9 temperature distribution in AIGaAslGaAs gain-guided laser arrays is in- vestigated. The FEM model is tested by comparing it with analytical solutions. For numerical convenience, the latter is rewritten in a novel form, which is free of overflow problems. The maximum temperatures calculated by both methods agree within 1%. Several factors determining ~he thermal resistance of the device are quantitatively examined: the ra~o of light emitting to non-emitting areas along the active zone, the amount of Joule losses, the current spreading, the solder thickness, and voids in the solder. This yields design rules for optimum thermal perform- ance. Keywords: finite element method (FEM), semiconductor Introduction High power semiconductor laser diodes [1, 2] find increasing use for pump- ing sol~d state lasers [3], material processing, and second harmonic generation [4]. The performance of such devices depends crucially on their thermal prop- erties, which are usually characterized through the thermal resistance, R~. The thermal resistance depends on the inner structure of the laser (layer thicknesses, thermal conductivities, location of heat sources) and on how the device is mounted on the heat sink (solder thickness and thermal conductivity, additional heat spreaders). Thus numerous theoretical and experimental investigations * Now at Gesellschaft f'tir F6rderung angewandter Optik, Optoelektronik, Quantenelektronik und Spektroskopie e. V., Rudower Chaussee 5, D-12489 Berlin, Germany 0368--4466/95/$ 4.00 9 1995 Akad~miai Kiad6, Budapest John Wiley & Sons, Limited Chichester