Maskless Fresnel zone plates for dense embedded optical components

Summary from only given. When an intense femtosecond laser pulse is tightly focused into a transparent material, high-order nonlinear absorption allows the energy to be deposited predominantly within the focal volume producing a permanent refractive index modification of up to 10/sup -2/ in the bulk of the transparent material. This process allows local patterning inside transparent media into 3D structures, allowing for instance the assembly of many optical components in a single glass block, producing rigid and environmentally tolerant devices. Using this simple technique of direct writing, we are able to write a maskless Fresnel zone plate (radius of 0.997 mm).