The present invention relates to a substrate comprising an ion-implanted layer, for example a cation, wherein the ion implanted layer has a substantially uniform distribution of the implanted ions at a significantly greater depth than previously possible, to a well-defined and sharp boundary within the substrate. The invention further comprises said sub-strate wherein the substrate is a silicon based substrate, such as glass. The invention also comprises the use of said material as a waveguide and the use of said material in measurement devices.