Self-heating effects at CW operation of MQW long-wavelength lasers

Based on a thermal lumped element model and on experimental results concerning the active region heating as a function of several injected current values, a very simple model involving self-heating effects has been implemented. The temperature rise in the active region of the laser due to current injection of magnitude I was calculated according to ΔT=aI+bI2−cL where a, b and c are coefficients which depend on the thermal resistance of the device and on the laser diode series resistance and turn-on voltage. L is the laser output power. Combining these results with those of the threshold current as a function of temperature, obtained for MQW long-wavelength lasers, we were able to analyze separately the effect of the diode thermal resistance, series resistance, turn-on voltage and characteristic temperature on the L–I curves. The calculated results seem to agree well with the experimental ones and may be used in the design of the laser structure in order to reduce self-heating effects.