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[(a)–(e)] Thermographic images of the front of laser A, obtained by synchronous undersampling lock-in thermography for different pulse widths (0.11, 1.1, 3.0, 17, and ) and an operation current of at 50% duty cycle. The dimensions of the laser die are , and the thickness of the heat spreader is . The stripe center is marked by a dashed vertical line and the coordinate system is indicated.
Temperature profiles, obtained as (a) horizontal -cuts and as (b) vertical -cuts through the images shown in Fig. 1 along the dotted lines. Full and dashed profile lines show data from devices A and B, respectively, for 0.11, 0.20, 1.1, 3.0, 17, and pulse widths in black, red, green, blue, cyan, and magenta, respectively. The main heat-flux directions are indicated by solid arrows. Dashed vertical lines indicate the device edges and center in (a) and the In solder between -mount and submount, the epilayer region, and the -contact, respectively, from left to right, in (b).
(a) Time evolution of the temperatures of the - (black) and -contact (blue) regions at the stripe center, normalized to that of the active region as derived from Fig. 2(b). Symbols mark experimental data of devices A and B, whereas lines represent results of FEM calculations. Solid lines stand for an ideal thermal contact across the solder and dotted lines for a nonideal one. (b) Temporal evolution of temperature profiles obtained from thermographic images of the side of the laser chip. The horizontal cuts through the active region and along the laser axis are normalized to the maximal camera signal at the front facet. The operation conditions and the line colors are the same as in Fig. 2.
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