Photonic crystal enhancement of Raman scattering†
Thin films of photonic crystals with inverse opal structure were prepared from opal-type templates by photocurable resin polymerization, and methylene blue dye was embedded into them as an analyte. Raman spectra were recorded at different angles of light incidence for samples with different positions of the stop band. A pure effect of the photonic stop band on the amplitude of spontaneous Raman scattering peaks for inverse opal samples without metallic nanoparticles was established for the first time. A great enhancement of the Raman spectra due to the coincidence of the stop band center with the laser wavelength was shown; the enhancement factor was estimated to be more than 50.