Fiber Fabrication

Optical Fiber Fabrication Technology

Optical fiber is used worldwide for transmission of voice, data, and content because of its ability to transmit at speeds in excess of 10 GB/second over very long distances.

Optical fibers consist of:

1. A core, having high refractive index. 2. Cladding. 3. Buffer, protective polymer layer. 4. Jacket, protective polymer layer.

Types of Fiber Based on Materials

1. Glass Fibers 2. Plastic Fibers 3. Photonic Crystal Fibers

Glass Fibers: • Glass Is Made by Fusing Mixtures of Metal Oxides, Sulfides or Selenite.

• Glass fiber is a dimensionally stable engineering material. Glass fiber does not stretch or shrink after exposure to extremely high or low temperatures.

• Glass fibers do not absorb moisture or change physically or chemically when exposed to water.

• Glass fiber is an inorganic material and will not burn or support combustion. It retains approximately 25% of its initial strength at 1000°F (540°C).

Plastic Optical Fibers:

• Plastic optical fiber (POF) (or Polymer optical fibre) is an optical fiber which is made out of Plastic.

• POF standard is based on multilevel PAM modulation a frame structure, Tomlinson-Harashima Precoding and Multilevel coset coding modulation.

• For telecommunications, the more difficult-to-use glass optical fiber is more common.

• Although the actual cost of glass fibers are similar to the plastic fiber, their installed cost is much higher due to the special handling and installation techniques required.

Photonic Crystal Fibers:

• Photonic-crystal fiber (PCF) is a new class of optical fiber based on the properties of photonic crystals.

• PCF is now finding applications in fiber-optic communications, fiber lasers, nonlinear devices, high-power transmission, highly sensitive gas sensors, and other areas

• PCFs guiding light by a conventional higher-index core modified by the presence of air holes.

• Photonic crystal fibers may be considered a subgroup of a more general class of microstructured optical fibers, where light is guided by structural modifications, and not only by refractive index differences.

Fiber Fabrication • Outside Vapor-Phase Oxidation(OVPO) • Vapor-Phase Axial Deposition(VAD) • Modified Chemical Vapor Deposition(MCVD) • Plasma-Activated Chemical Vapor

Deposition(PCDV) • Photonic Crystal Fiber Fabrication.

Outside Vapor-Phase Oxidation(OVPO):

• The preform, as mentioned above, is nothing more than an optical fiber but on a much larger scale.

• Drawing enables the manufacturer to obtain the fiber in the actual size desired.

• First a Layer of Sio2 Particles Called a Soot is deposited from a burner onto a Rotating Graphite Or Ceramic Mandrel.

Vapor-Phase Axial Deposition (VAD):

• This was the first successful mass-fabrication process. It was developed by Corning in 1972. In fact, the first optical fiber with attenuation less than 20 dB/km was manufactured by Corning using this process.

• The process consists of four phases: laydown, consolidation, drawing, and measurement .

Modified Chemical Vapor Deposition(MCVD):

• This process was developed by Bell Laboratories in 1974 and has been widely accepted for the production of graded-index fiber.

• First, reactant gases flow through a rotating glass tube made from fused silica while a burner heats its narrow zone by traveling back and forth along the tube.

• SiO2, GeO2, and other doping combinations form soot that is deposited on the inner surface of the target tube.

Plasma-Activated Chemical Vapor Deposition(PCDV):

• This process was developed in 1975 by Phillips, a Dutch consumer-electronics and telecommunications company.

• The process differs from MCVD in its method of heating the reaction zone: Instead of delivering heat from the outside through a burner, PCVD uses microwaves to form ionized gas—plasma—inside the silica tube.

• The capacity of this preform is about 30 km of fiber.

Photonic Crystal Fiber Fabrication: