High performance quantum cascade laser frequency combs at λ ~ 6 pm

We present efficient quantum cascade laser frequency combs at 6 μm, operating from −20°C to 50°C, with a maximum total (two facets) output power of 520 mW. The dispersion of the waveguide is carefully engineered with the help of plasmonic-waveguide method to achieve efficient comb operation. 3mm, 4.5 mm and 6 mm-long devices were tested with various ridge-widths (from 2.8 μm to 5.5 μm). All the devices showed comb operation at all measured temperatures proving the reliability of the plasmonic-waveguide method.