Efficient third-harmonic generation in asymmetric In_xGa_1-xN/InN double quantum wells

We report on enhanced third-harmonic generation based on intersubband transitions in an asymmetric In_xGa_1-xN/InN double quantum well. We give a comprehensive account of the influences of different structural parameters such as doping concentration, thickness of layers, and indium mole composition of barriers on the intersubband transition quantities and then their nonlinear response. The conduction band parameters are computed by the numerical solution to Schrödinger and Poisson equations within nonparabolic band approximation. More importantly, the participation of each electron scattering process, e.g., LO phonon scattering in the electron relaxation time and linewidth values, is calculated, so that it can be considered a reference to provide a heterostructure with optimum functionality. Finally, two optimized double quantum wells are designed at the fundamental photon energies of 117 and 144 meV, which exhibit remarkable third-order susceptibility up to $1.2×10−3$ and $10−3μm2/V2$⁠, respectively. This study opens a new path to design a suitable In_xGa_1-xN/InN heterostructure for a third-harmonic generation process from the far- to near-infrared band, which promises various applications in optoelectronic devices.