We will describe a new refractive index imaging system in a solid organic polymer medium, based on the photoinitiated isomerization of Dewar benzene derivatives. The system exhibits a refractive index contrast of >0.02, with very low dimensional changes upon recording. Furthermore, the medium is highly sensitive because the recording process is chemically amplified, (i.e., many product molecules are formed per photon absorbed). The change in refractive index occurs spontaneously under blue or UV irradiation; no subsequent processing of any kind is required. This system may find applications in holographic recording and for integrated optical devices. For example, >50 spatially overlapping diffraction gratings were recorded in the material in ±2 degrees (angular multiplexing).