Large interband second-order susceptibilities in InxGa1−xN/GaN quantum wells

Abstract
We present measurements of second-harmonic generation in interband transitions of InxGa1−xN/GaN multiple quantum well samples. The second-order susceptibility χ(2) is studied as a function of pump wavelength and quantum well width. For the narrowest wells, we obtain χ(2)=1.3±0.4×10−10 m/V, which is an order of magnitude larger than the intrinsic value for bulk GaN. The corresponding power conversion efficiency was 6.3×10−7. An enhancement of the nonlinearity due to strong internal piezoelectric fields could not be observed.