Temperature dependence and single-mode tuning behavior of second-harmonic generation in quantum cascade lasers

Second-harmonic generation (SHG) is reported in quantum cascade (QC) lasers with active regions that also support nonlinear cascades with large second order nonlinear susceptibility. SHG has been measured from 10 up to 250 K heat sink temperature, with about 1 muW of nonlinear power at 10 K and about 50 nW at 250 K. Single-mode and tunable SHG at 3.5 mum wavelength has been measured from single-mode QC distributed feedback lasers operating at the fundamental pump wavelength of 7.0 mum. Thermal tuning results in a tuning rate for the SHG emission of similar to0.2 nm/K for temperatures above similar to100 K. (C) 2004 American Institute of Physics.