Stimulated Raman scattering from Mie-resonant subwavelength nanoparticles.

Resonant dielectric structures have emerged recently as a new platform for subwavelength non-plasmonic nanophotonics. It was suggested and demonstrated that the multipolar magnetic and electric Mie resonances can enhance substantially many effects at the nanoscale including spontaneous Raman scattering. Here we study experimentally stimulated Raman scattering (SRS) in isolated silicon (c-Si) nanoparticles and observe a transition from spontaneous to stimulated scattering manifested in a nonlinear growth of the signal intensity above a certain pump threshold. At the Mie resonance, light gets confined into a low volume of the resonant mode with higher intensity of the electromagnetic field inside the c-Si nanoparticle due to its high refractive index, which leads to overall strong SRS at low pump intensities. Our finding paves the way to the development of efficient Raman nanolasers for multifunctional photonic metadevices.