Tuning the Δn and scattering in Bayfol® HX based holograms

Abstract Self-developing photopolymers are crucial materials for making high efficiency volume holograms. A key feature is the tuning of the refractive index modulation (Δn), but at the same time, it is crucial to minimize the light scattering which reduces the efficiency and increase the unwanted light. Here, we study Bayfol® HX materials in terms of scattering formation and control of the Δn by means the realization of Volume Phase Holographic Gratings (VPHGs), which are intended for the application in spectroscopic instrumentation. We highlight the dependency of the Δn and scattering with the laser light intensity, showing that the increase of the intensity reduces the amount of scattering. In addition, the fine tuning of the Δn with the incoherent light pre- and co-exposure is studied and the full dynamic range can be addressed controlling the scattering. A modified diffusion model is also used to describe and predict the experimental results.