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

Nanostructures enabling light manipulation in response to external stimuli offer unprecedented opportunities for efficient control over optomechanical systems at the nanoscale. The integration of stimuli-responsive materials in such systems is an important milestone in the creation of miniaturized and smart nano- and micromechanical systems. In this article, a thermally sensitive mechanically driven platform based on pNIPAM microspheres modified with high refractive index dielectric silicon (Si) and plasmonic gold (Au) nanoparticles is presented to probe the temperature-dependent reversible mechanical transformations through the second-harmonic generation signal switching. The second-harmonic generation process is investigated theoretically and experimentally depending on the applied temperature and pNIPAM phase. It is found that the change of the interparticle distance in the system during the phase transition provokes generation of optically induced static electric field probed by the second-harmonic generation signal. The obtained results can become the foundation in the creation of nanophotonic devices based on thermo-sensitive polymers, as they combine reversible tuning of optical signals with the opportunity of local probing of mechanical changes.

Automated summary

This article presents a thermally sensitive mechanically driven platform based on pNIPAM microspheres to probe temperature-dependent reversible mechanical transformations and switch the second-harmonic generation signal. The results provide a foundation for the creation of nanophotonic devices based on thermo-sensitive polymers that combine reversible tuning of optical signals with local probing of mechanical changes.