1. Introduction

The holographic recording materials are traditionally used to record holograms, and they have been mainly studied and characterized for holographic applications [1–3]. Along with the evolution of photonics, communications and optical processing of information, the relevance, and capabilities of these materials to store any kind of phase or amplitude diffraction pattern, with good results also for low spatial frequencies, are surfacing [4–6]. At this point, the complete characterization of these materials for low spatial frequencies is decisive to design a material with the optimum characteristics for each specific application [7, 8].

The holographic recording materials change their properties when they are exposed to the light, and there are many examples of them, for example, the photographic emulsions [9], photochromic materials [10], dichromated gelatin [11], photorefractive materials [12], or photopolymers [13].

The last ones, photopolymers, are a very promising option, for example, for the development of holographic memories due to its high resolution and fidelity. The use of this recording material has spectacularly been increased because of its versatility at the time of changing their composition or design [14]. Moreover, they present high reliability, repeatability, and flexibility together with their tunable thickness, self-processing capabilities, and low cost. It is undeniable how those features set the photopolymers as one of the best holographic storage media and a good option for applications inside the diffractive optics and optical processing fields.

In these fields, one of the main drawbacks to be faced is the conservation of the element recorded into the photopolymer. In this sense, along this chapter, we will study the effects and improvements added by a coverplating together with an index-matching system. This system not only improves the lifetime of the material but also affects to the molecules diffusion inside the material.
