  We report here chiroptical amplification effect occurring in the hybrid
systems consisting of chiral molecules and Si nanostructures. Under resonant
excitation of circularly polarized light, the hybrid systems show strong CD
induction signals at optical frequency, which arise from both the electric and
magnetic responses of the Si nanostructures. More interestingly, the induced CD
signals from Si-based dielectric nanoantennas are always larger than that from
Au-based plasmonic counterparts. The related physical origin was disclosed.
Furthermore, compared to the Au-based high-loss plasmonic nanoantenas, Si-based
low-loss structures would generate negligible photothermal effect, which makes
Si nanoantennas become an optimized candidate to amplify molecular CD signals
with ultralow thermal damages. Our findings may provide a guideline for the
design of novel chiral nanosensors for applications in the fields of
biomedicine and pharmaceutics.
