Enhanced Raman scattering in multilayer structures of porous silicon

Multiple enhancement of the Raman scattering efficiency is observed in porous-silicon-based one-dimensional photonic bandgap (PBG) structures with tunable reflection and dispersion under excitation at 1.06 µm. The experimental results are explained as being due to the resonant increase in the effective Raman susceptibility at light wavelengths close to the PBG edges. This effect is discussed in view of possible applications in the Raman spectroscopy of molecules embedded in porous media as well as in the Raman laser based on silicon. Copyright c � 2011 John Wiley & Sons, Ltd.