Ion implantation and ion mixing have made possible the production of new materials having new properties and new phases or structures. Typically, the optical properties modification of material by implantation strongly depends on the chemical bonding in the matrix. In the particular case of insulators these modifications can result in two different ways : the creation of intrinsic defects associated with energy loss processes (electronic excitations or nuclear collisions) and extrinsic defects due to the doping. The defect concentration is inhomogeneous in depth as the energy loss profiles which is very usefull for waveguide applications to obtain a refractive index gradient or a coloration gradient. The implantation of chemically reactive ions in materials is a non conventionnal way of doping. Bonding and charge transfert effects can induce strong modifications of the optical properties of the implanted layer. In addition for heavily implanted materials, new phases can be formed by precipitation processes such as small metallic clusters embedded in an insulator. Their implications in solar energy conversion are important for selective absorber production.