Fig. 5: The regrowth planarization technique of QCLs. | Light: Science & Applications

Fig. 5: The regrowth planarization technique of QCLs.

From: High-power, high-wall-plug-efficiency quantum cascade lasers with high-brightness in continuous wave operation at 3–300μm

Fig. 5

a Schematic of the processing flow for the redesigned buried ridge process. b The SEM image of an epilayer-down bonded undergrown QCL device (upper panel) and the device thermal distribution simulated with the finite-element method (lower panel). c The SEM image of an epi-down bonded planarized QCL device using the redesigned processing technique (upper panel) and the thermal simulation result of the device (lower panel). The two simulation figures share the same scalar bar to reflect the internal temperature difference for the two cases. The white bars on the SEM images represent a length scale of 10 μm. d P–J–V characterizations for the undergrown and planarized QCLs in pulsed mode operation (d) and in CW operation (e)7

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