Nanocomposites based on bare synthetic opals soaked with the Bi12SiO20, Bi2TeO5 and NaBi(MO4)2 melts are characterised by employing scanning electron microscopy, Bragg light reflection and FTIR and Raman spectroscopy technique. Crystalline state of the substance inside opal pores is proved for all composites. The formation of bismuth orthosilicate and tridymite and its phases is proposed in ‘opal–Bi12SiO20’ and ‘opal–Bi2TeO5’ composites, respectively. Raman spectrum of ‘opal–NaBi(MoO4)2’ is not essentially changed compared to that of the single crystal, except for a shift of one Raman band and appearance of one weak new band. The reasons for spectral intensity redistribution revealed by micro-Raman surface scanning may be both the composition inhomogeneity and the structural light focusing together with concentration of the exciting radiation field nearby the surface and bulk defects.