Tunable nanoswitches based on nanoparticle meta-molecules.

We introduce ultra-fast tunable nanoswitches based on the transition between states of nanoparticle meta-molecules. These molecules are formed (activated) when hybrid systems consisting of metallic nanoparticles and semiconductor quantum dots interact with coherent light sources (laser fields). The switching process occurs via minuscule changes of the refractive index of the environment or the distance between the quantum dots and metallic nanoparticles. These changes stimulate the transition between the states of the meta-molecules in nanosecond timescales, setting up dramatic optical events that can be observed easily. These nanoswitches can be tuned by varying the intensity of the activating laser field, allowing us to adjust the switching process to occur at different values of refractive indices. The results open a new horizon for chemically, biologically, or physically triggered optical nanoswitches and nanosensors that are sensitive to ultra-small changes in the environment.