Reflection HOEs recorded on photopolymerisable glass layers: a step towards holographic mirrors for AR technologies

Reflection Holographic Optical Elements (HOEs) offer a great potential for Augmented Reality (AR) display technologies due to their unique capability to redirect light with the predetermined wavelength in the opposite direction to the reconstructing light. AR displays based on HOEs enable a large variety of potential applications which necessitates the development of HOEs with long-term stable performance in challenging ambient conditions. Here, we present a study of the holographic recording capability of a photopolymerizable hybrid sol-gel (PHSG) which has shown to be a robust and water/temperature resistant material. Using optimal recording conditions, diffraction efficiency up to 18% has been achieved in reflection gratings with a spatial frequency of (5300 ± 50) lines/mm. Effective shrinkage of the PHSG reflection gratings is found to be 1.2 ± 0.2% which is close to values reported for the state-of-the-art photopolymers. Thus, this research provides further evidence of the practical potential of PHSG for the HOE development for applications requiring long-term environmental stability and durability.