Raman enhancement via double optical resonances in all-dielectric photonic crystal slabs

All-dielectric photonic structures are an important class of substrates in surface-enhanced Raman spectroscopy (SERS), utilizing optical resonant modes to significantly enhance the electromagnetic field and amplify the Raman signals. In this study, we demonstrate the double-resonance approach to realize significant Raman enhancement using all-dielectric photonic crystal (PhC) slab. The double-resonance condition is satisfied by designing optical resonant modes in photonic bands to match frequencies of both excitation laser and Raman signals. By the fabricated PhC slab, the significant enhancement for the Raman signal of silicon is demonstrated. The enhanced Raman signals exhibit a uniform distribution on the PhC slab. The method of Raman enhancement via double optical resonances can advance the field of all-dielectric SERS and holds potential for future SERS applications.