High power and single mode quantum cascade lasers

We present a single mode quantum cascade laser with nearly 1 W optical power. A buried distributed feedback reflector is used on the back section for wavelength selection. The laser is 6 mm long, 3.5 mu m wide, mounted episide-up and the laser facets are left uncoated. Laser emission is centered at 4.68 mu m. Single-mode operation with a side mode suppression ratio of more than 30 dB is obtained in whole range of operation. Farfield measurements prove a symmetric, single transverse-mode emission in TM00-mode with typical divergences of 41 degrees and 33 degrees in the vertical and horizontal direction respectively. This work shows the potential for simple fabrication of high power lasers compatible with standard DFB processing. (C) 2016 Optical Society of America