Fabrication of cylindrical active GRIN media by laser-assisted radial dopant diffusion: A proof of concept

•Laser Zone Melting process is proposed for fabrication of active GRIN media.•A CO2 laser source is used to promote the gradual diffusion of optically active ions or materials in silica rod substrates.•A higher degree of diffusion is observed for SiO2 rods doped with LiNbO3. This work introduces a new approach to prepare active GRadient-INdex (GRIN) materials by gradually doping commercial silica cylindrical substrates with different optically active ions or materials by the Laser Zone Melting (LZM) process. Scanning Electron Microscopy (SEM) combined with energy dispersive X-ray (EDX) analysis demonstrate that the dopants are gradually incorporated into the cylindrical substrate under controlled penetration depths. This simple, environmentally respectful fabrication method opens the possibility to manufacture versatile GRIN optical elements on a large scale and reduced cost.