The realization that modulated light pulses can be transported in a confined fashion over long distances within a structure that comprises a controlled spatial distribution of the refractive index nas in optical fibres and waveguideshas, without doubt, underpinned the telecommunications revolution witnessed during the 20th century. The refractive index n, quantifying how light propagates in a given medium, as a consequence, has become one of the most important materials properties in designing photonics products. The other key characteristic for most optical and photonic applications is the amount of light that is absorbed by a material, expressed as the extinction coefficient Although a range of organic/inorganic hybrid materials have been advanced with tunable refractive index, only a few systems combine a high n, sufficiently low ? and straightforward sample preparation to allow simple fabrication of highly transparent, low-loss structures. Here, we present a hybrid material that can be readily produced in water via a one-pot synthesis directly from commercially available, low-cost precursors. Moreover, our hybrid material can be solution-processed, yielding systems of an extinction coefficient <0.01, and a refractive index, which can be controlled to adopt values between 1.5 to at least 2.1. Unprecedentedly, simple post-deposition procedures such as thermal annealing or irradiation with high-intensity UV-light allow adjusting n also after film fabrication, offering an exceptional degree of freedom in designing and tailoring also more complex photonic architectures or planar wave-guides, for example, through creation of in-plane refractive index patterns. As a proof-of-concept, we demonstrate fabrication of waveguides based on local heating. The versatility of our materials is further illustrated by the production of lenses and dielectric filters of similar to 100% reflectivity in a given wavelength regime. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 000: 000000, 2011