Multipole polarization assisted optical bistability in a semiconductor quantum dot/metal nanoparticle hybrid molecule

We theoretically study the optical bistability assisted by multipole polarizations in a semiconductor quantum dot (SQD)/metal nanoparticle (MNP) hybrid molecule. We map out bistability phase diagrams within the parameter subspace spanned by (the pumping intensity Ipu, interparticle distance, d) under dipole and multipole approximations. It is shown that the Ipu-correlated bistable region will be broadened greatly in the strong exciton–plasmon coupling regime, and the corresponding lower (upper) bistable threshold is enlarged significantly due to multipole polarization (N = 10) in comparison to that in the dipole approximation (N = 1). However, under the same conditions, the d-correlated bistable region is shrunk at high pump intensities. Our contribution not only offers a better understanding of exciton–plasmon coupling systems but also expands the application of SQD/MNP hybrid molecules in the field of optical bistable nanodevices.