Thermally Induced Mechanical Switching of the Second-Harmonic Generation in pNIPAM Hydrogels-Linked Resonant Au and Si Nanoparticles

摘要

Nanostructures enabling light manipulation in response to external stimulioffer unprecedented opportunities for efficient control over optomechanicalsystems at the nanoscale. The integration of stimuli-responsive materials insuch systems is an important milestone in the creation of miniaturized andsmart nano- and micromechanical systems. In this article, a thermally sensitivemechanically driven platform based on pNIPAM microspheres modifiedwith high refractive index dielectric silicon (Si) and plasmonic gold (Au)nanoparticles is presented to probe the temperature-dependent reversiblemechanical transformations through the second-harmonic generation signalswitching. The second-harmonic generation process is investigated theoreticallyand experimentally depending on the applied temperature and pNIPAMphase. It is found that the change of the interparticle distance in the systemduring the phase transition provokes generation of optically induced staticelectric field probed by the second-harmonic generation signal. The obtainedresults can become the foundation in the creation of nanophotonic devicesbased on thermo-sensitive polymers, as they combine reversible tuning ofoptical signals with the opportunity of local probing of mechanical changes.