Terahertz sources based on intracavity frequency mixing in mid-infrared quantum cascade lasers with passive nonlinear sections

We report the design and performance of terahertz quantum cascade laser sources based on intracavity difference frequency generation in dual-wavelength mid-infrared quantum cascade lasers with a passive nonlinear section at the exit facet, designed for giant second-order nonlinear susceptibility. These devices operate in the mid-infrared at lambda(1) = 8.4 mu m and lambda(2) = 9.5 mu m, with terahertz output at the difference frequency, lambda(3) approximate to 73 mu m. Terahertz output of approximately 100 nW was observed up to a heat sink temperature of 210 K. (C) 2011 American Institute of Physics. [doi:10.1063/1.3579260]