The MCVD process is one of several processes for manufacturing gradient fibers
. In the MCVD process, a glass tube is coated from the inside and the fiber core is only introduced at the end. A gas mixture is added to the fused silica to determine the refractive index. By repeatedly feeding and changing the gas mixture, layers with different refractive indices are produced. Other manufacturing processes for optical fibers are Plasma Activated Chemical Vapor Deposition (PCVD) and Outside Vapor Deposition (OVD).