Tailoring SHG Nonlinearities in Asymmetric Triple Quantum Wells: The Interplay Between Potential Configuration and Intense Laser Field Tunability

This study investigates the effect of an intense laser field (ILF) on the nonlinear optical properties of four asymmetric triple quantum well (ATQW) structures with distinct potentials: the asymmetric triple graded QW (ATGQW), the asymmetric inverse triple graded QW (AITGQW), the asymmetric triple semi-parabolic QW (ATSPQW), and the asymmetric inverse triple semi-parabolic QW (AITSPQW). Variations in confined energy levels, dipole moment matrix elements (DMMEs), and second harmonic generation (SHG) coefficients were analyzed as a function of the ILF parameter (α 0 ). The ILF causes substantial structural deformation in all ATQWs, especially the AITGQW, which nearly becomes an asymmetric single well at α 0 = 6 nm. The optimal SHG response is highly sensitive to the interplay between potential geometry and the ILF. The ATSPQW exhibits its maximum SHG peak at α 0 = 6 nm, whereas the AITGQW, AITSPQW, and ATGQW peak at α 0 = 3 nm. At α 0 = 0, the AITSPQW shows the largest DMME product; at α 0 = 9 nm, the AITGQW exhibits the smallest. These findings highlight the crucial role of potential asymmetry and ILF-induced modulation in tailoring QW optical nonlinearities for tunable, high-efficiency optoelectronic and nanophotonic devices.