In this work it is shown the first characterization of holographic solar concentrators recorded in Biophotopol -one of the greenest photopolymers. Biophotopol is an acrylate-based and water-soluble photopolymer with good recycling properties. The composition of this photopolymer and their thickness are easily changeable, which implies an important advantage vs. others commercialized photopolymers. Good diffraction efficiency and wide acceptance angles are achieved on phase volume transmission holograms by using an optimized composition and thin layers. A curing stage with a white incoherent light has been performed to obtain high temporal stability together with a good diffraction efficiency. Finally, the performance of the holographic lenses as holographic solar concentrators has been evaluated with an electronic setup connected to a polycrystalline silicon photovoltaic cell and a high intensity solar simulator emitting a standard solar spectrum (AM1.5G).

The holographic principle, discovered by Gabor, and realized by Leith & Upatnieks and Denisyuk is discussed. The intrinsic value of this idea and its continuing ability to motivate and inspire engineers and applied physicists is reviewed.

A historical review of the origins of holography is presented. Special emphasis is placed on the contributions of Gabor, Denisyuk and Leith to the development of holography, to motivate and inspire students and young researchers.

The technologies based on holographic and photonic techniques related to the optical storage and optical processing of information are rapidly evolving. One of the key points of this evolution are the new recording materials able to perform under the most specific situations and applications. In this sense, the importance of the photopolymers is growing spectacularly. This is mainly due to their versatility in terms of composition and design together with other interesting properties such as self-processing capabilities. In this chapter, we introduce the diffractive optical elements (DOE) generation in these materials and some of the most important parameters involved in this process. The deep knowledge of the material is essential to model its behavior during and after the recording process and we present different techniques to characterize the recording materials. We also present a 3D theoretical diffusion model able to reproduce and predict the experimental behavior of the recording process of any kind of DOE onto the photopolymers. The theoretical results will be supported by experimental analysis using a hybrid optical-digital setup, which includes a liquid crystal on silicon display. Besides this analysis, we study a method to improve the conservation and characteristics of these materials, an index-matching system.

The recording of volume holographic reflection gratings in eco-friendly photopolymers represents a challenge at present since they can be used in many important applications such as holographic optical elements and biosensors. In this sense, the aim of this work has been fabricated reflection gratings in the symmetrical experimental in "Biophotopol" and to study the dependence of diffraction efficiency on physical thickness, recording intensity and exposure energy. An increase in diffraction efficiency was observed when the photopolymer films were cured with a LED lamp to improve the stability of the reflection holograms. The maximums diffraction efficiencies around 30 % were obtained for reflection gratings with a spatial frequency of 4888 lines/mm. The index modulation and optical thickness were obtained by fitting procedure through Kogelnik's coupled wave theory. Experimental and theoretical results have been interpreted to modify the photopolymer formulation and exposure conditions in order to increase the diffraction efficiencies.