Transient thermal behavior of high power diode laser arrays

Reliability and lifetime of high power laser arrays are governed by their t hermal properties. Thus the understanding of the thermal behavior such as t hermal transients as well as the optimization of laser chips and mounting a re key features for obtaining improved devices. We present numerical simula tions of the active layer temperature employing the finite element method ( FEM). Both continuous wave (cw) operation and thermal transients are modele d within a unified theoretical concept, which basically connects a balance equation model that provides information on the temperature dependence of t he loss mechanisms, such as spontaneous emission, Auger and surface recombi nation with a 2 dimensional FEM model. For a given laser array architecture we calculated the effect of the introduction of different heat spreader ma terials such as copper, silicon and diamond. Furthermore, different array d esigns such as broad area devices and stripe arrays having different output power (cm: 1-10 W) are numerically described. These results are compared with experimental data on the averaged temperatu re of the optically active layer. The temperature values are determined fro m the spectral shift of the emission spectrum of the array at a certain tim e windows after applying the operation current. Both experimental and theor etical results are compared from the 10 ns to the cw range. Thus both the t heoretical description concept as well as the parameter set used for the ca lculation are carefully tested. Remarkable agreement between calculated and measured thermal transients was found. Additionally the very divergent tem poral behavior of special array structures was verified coincidentally by t heory and experiment.