Enhanced Raman scattering in a colloidal crystal observed by a tunable laser light source

The Raman scattering intensity was measured for a colloidal crystal composed of polystyrene micro spheres and a polymer gel with a tunable continuous-wave dye laser as an excitation light source. Enhancement of the Raman scattering caused by both the electric field enhancement at the excitation frequency and the increase in the local photon density of states at the scattering frequency was expected. The observed Raman scattering intensity as a function of the excitation frequency showed a reasonable agreement with the theoretical prediction.