A process comprises (a) providing a substantially inorganic photoreactive composition comprising (1) at least one cationically reactive species, (2) a multi-photon photoinitiator system, and 10 (3) a plurality of precondensed, inorganic nanoparticles; (b) exposing, using a multibeam interference technique involving at least three beams, at least a portion of the photoreactive composition to radiation of appropriate wavelength, spatial distribution, and intensity to produce a two-dimensional or three-dimensional periodic pattern of reacted and non-reacted portions of the photoreactive composition; (c) exposing at least a portion of the non-reacted portion of the photoreactive composition to radiation of appropriate wavelength and intensity to cause multi-photon absorption and photoreaction to form additional reacted portion; (d) removing the non-reacted portion or the reacted portion of the photoreactive composition to form interstitial void space; and (e) at least partially filling the interstitial void space with at least one material having a refractive index that is different from the refractive index of the remaining portion.