Tailoring Kerr nonlinearity in a quantum dot-metallic nanoshell-cell membrane hybrid system for high-sensitivity...

We develop a theory to investigate Kerr nonlinearity in a hybrid nanosystem integrating a semiconductor quantum dot (SQD), a metallic nanoshell (MNS) consisting of a metallic inner core and a dielectric outer shell, and a cell membrane. Beyond the dipole approximation, an analytical expression for the Kerr coefficient is derived, with key findings as follows: (1) The multipole effect enables a significant enhancement of the Kerr coefficient compared to the dipole approximation scenario, whereas increasing the spacing between the SQD and the MNS leads to substantial suppression of this coefficient; (2) The Kerr spectrum can be switched from a two-peaked to a three-peaked structure solely by tuning the exciton-phonon coupling strength; (3) The heights, positions, and full widths at half maximum (FWHM) of the two sideband peaks in the Kerr spectrum exhibit high sensitivity to both pumping intensity and dielectric shell thickness. Importantly, we demonstrate the feasibility of detecting the initiation of normal cell carcinogenesis by monitoring the heights, locations, and frequency shifts of these two sideband peaks. The proposed scheme exhibits promising applications in quantum information networks and biosensing.