Abstract
Enhancing radiative transitions including spontaneous emission and scattering of silicon (Si) has been of
interest for realizing light emitting and quantum optical devices. Here, we demonstrate enhancement of
Si spontaneous emission using ultrasmall and high-Q Si photonic crystal (PhC) cavities via the Purcell
effect because the emission of bulk Si is quite weak due to its indirect energy band structure. The
photoluminescence of electron-hole droplets in Si PhC cavities is resonantly increased by a factor of
140. In addition, we observe enhancement of spontaneous Raman scattering of carbon nanotubes by Si
PhC cavities. These approaches for cavity-enhanced radiative transitions show another useful way for
realizing Si-based optical devices.
