Kerr birefringent switching mechanism in core-shell nanowires transformed by stark anti-crossing

Stark anti-crossing (SAC) serves as a new approach to switch the Kerr birefringence effect of the off-centered core-shell square nanowires (OSN). The intensity of SAC induced by an electric field is inversely correlated with the degree of the core displacement from the center. To the best of our knowledge, it is the first demonstration that SAC is equipped with efficacy in suppressing Kerr birefringence of OSN by intensifying energy degeneracy and mitigating the parity symmetry distortion of wavefunction due to core displacement. Such a novel mechanism lies in the formation of two quasi-degenerate energy levels with nearly identical energies but opposite parity wavefunctions. It demonstrates a transform from polarization-dependent to -independent response of refractive index changes at mid-infrared wavelengths longer than 10 µm.