Stability analysis of symmetric holographic transmission gratings stored in photohydrogels

The development of advanced holographic materials is a constantly evolving field of research, driven by the need to adapt their optical properties to the specific demands of photonic devices. In particular, photohydrogels emerge as promising materials for applications in liquid media because of their ability to maintain structural integrity under high-humidity conditions. This work focuses on evaluating the structural stability of unslanted transmission volume phase holograms stored in photohydrogels based of acrylamide and N,N′-methylenebis(acrylamide). The influence of radiant exposure on diffraction efficiency has been analyzed on holographic gratings stored at two different spatial frequencies. For this purpose, a theoretical model based on the theories of Kogelnik, Kubota and Uchida has been used, considering the influence of bending and attenuation of holographic gratings in depth. This approach allows us to understand how these deformations affect the diffraction efficiency and the internal structure. This can provide key information for the design of devices in which holograms stored in photohydrogels are used.