Fig. 11: The optical damage mitigrated long-wave mid-infrared QCL. | Light: Science & Applications

Fig. 11: The optical damage mitigrated long-wave mid-infrared QCL.

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

Fig. 11

Optical images of the interface between the taper and the QCL device with (a) lower and (b) higher magnification. c SEM image of the back facet of the buried ridge QCL device. d SEM image of the taper side facet of the buried ridge QCL device. e LIV-WE curves of the QCL with a tapered structure. Inset: the spectrum of the laser emission at 3 A. f Far field of the QCL at different current injections in CW operation. g LIV curves of the tapered QCLs with DFB gratings targeted at λ ≈ 8 and 9 μm, respectively. Inset: the far field of the QCL at λ ≈ 8 μm with an injection current of 1.8 A. h Spectra of the two lasers as a function of current from 1.4 to 2.6 A65

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