Nanomaterials are mainly categorized into three groups: fundamental building blocks, dispersions or composites of building blocks in randomly ordered matrices, and spatially resolved, ordered nanostructures. Today, nanomaterials that offer some unique optical properties may find application as pure materials or may be integrated into larger structures. This book presents examples of both pure and composite materials that include organic–inorganic nanocomposites and quantum dots embedded into different matrices for various applications in modern nanotechnology.