Modified chemical vapor deposition, MCVD
Fibercore manufactures its fibers by MCVD, which involves the deposition of glass particles on the inside wall of a substrate tube to form the fiber inner cladding and core structure. To form a simple optical fiber silicon chloride, SiCl4 and germanium chloride, GeCl4 are oxidized to form silica and germania particles.
These adhere to the inside of the tube due to the thermophoretic force, and are then sintered into an amporphous glass layer. Once the desired number and composition of layers has been deposited, the tube is heated and collapsed into a rod – which is ready to be drawn into fiber.