Porous silicon based one-dimensional photonic crystals, such as Bragg mirror and optical microcavity, has been modified by infiltration of a new biocompatible polymer, an amino functionalized poly(ε-caprolactone) (PCL-NH2), and characterized as optical biochemical sensors. The entrapped polymer adds strong chemical stability to the nanocrystalline matrix on exposure to alkaline solutions preserving the device sensing abilities in monitoring volatile substances and chemical compounds. On the basis of these results, these hybrid structures can be proposed as a high performance platform for biochemical applications.