Fiber preform is an upstream product with high technical content, and scarce supply in the optical fiber and cable industry. It is mainly used for the drawing of optical fibers. Fiber preform is a cylindrical high-purity quartz glass rod. Its structure is divided into two parts. The core rod in the center is made of glass material with a higher refractive index, while the cladding on the surface is made of glass material with a lower refractive index. The difference in refractive index enables the reflection and transmission of optical signals.
The current manufacturing processes for preformed rods mainly include:
1.Vapor axial deposition (VAD), where a high-temperature gaseous reactant deposits to form a glass layer at the end of the rotating rod core.
2.External vapor deposition (OVD), where the deposition occurs on the outside of the rotating rod core.
3.Modified chemical vapor deposition (MCVD), where a glass layer is deposited on the inner wall of a quartz tube and then undergoes high-temperature melting and crystallization.
4.Plasma chemical vapor deposition (PCVD), where a glass layer is deposited using plasma to excite the gas, suitable for high-performance fiber production. The cladding of the fiber preform rod can be manufactured using the large tube method (RIC) process, where the core rod is placed inside a high-purity quartz tube and then locally heated to integrate the entire component, or using the OVD method to deposit the cladding part on the side of the rod core.
These processes generate oxide particles through gas-phase reactions and deposit them. After being sintered at high temperatures, they form transparent glass rods.
