Transient thermal characteristics related to catastrophic optical damage in high power AlGaAs/GaAs laser diodes

Abstract

The transient thermal characteristics related to catastrophic optical damage (COD) in high power AlGaAs/GaAs laser diodes (LDs) are studied experimentally by means of thermal infrared imaging, laser scanning confocal microscopy, and transient thermal technique. The transient thermal technique is based on the diode forward voltage method in which the structure function theory is applied to determine the component thermal resistance and temperature rise of the LDs. We have recorded the dynamics of COD process using thermal infrared camera. Two melting spots are observed in the output facet after COD which location exactly matches the position of the thermal flash from the thermal imaging and even the temperature of COD seed has a sudden increase of 32 K when the COD event occurs. Furthermore, we find that the thermal resistance from chip to In solder increases remarkably after COD, meanwhile the thermal resistance of solder and package does not change apparently. The results are attributed to the heat power dissipation increase originating from the enhancement of nonradiative recombination after COD under constant input electrical power.

Thermomechanical issues of high power laser diode catastrophic optical damage

“…This equation was solved using the method of Green's functions and, after imposing the necessary boundary and initial conditions, the time-dependent temperature profiles for the laser were computed. A comparison between the results for catastrophic degradation times vs. amplitude of the pulses as derived from the models by Henry et al [31], Kappeler et al [34] and Nakwaski [35], is shown in Figure 7.…”

“…Nakwaski [50] extended the work by Henry et al [31]. While accepting the same assumptions about the heat generation at the surface of the DH laser, explicit temperature dependences were considered for the thermal conductivity and diffusivity.…”

“…Comparison with the experimental data reported in the same work showed a reasonable agreement in the computed solutions. Regardless of its possible shortcomings, the work by Henry et al steered interest in the field and several publications with further developments followed shortly [31].…”

“…Despite not being adequate for the precise determination of the critical temperature launching COD, thermal infrared imaging (TII) [23][24][25][26][27][28] and time-resolved electroluminescence (TR-EL) [29][30][31][32] have been used to monitor the degradation of laser diodes under progressively increasing bias currents [23,33], pulsed high power operation [24,25,27,28], and CW accelerated [29,31,34] or low-stress [28,32,35] lifetests. Some relevant aspects of COD have been clarified with these techniques.…”

“…Some relevant aspects of COD have been clarified with these techniques. In TII experiments the thermal runaway effect of COD is detected by the camera as a thermal flash [24,33]. This event has been demonstrated to be an extremely fast (hundreds of ns) [36] and spatially confined effect [23].…”