Fused silica rods for optical fiber

High purity fused silica rods generally serve one of three purposes in optical fiber production:

  • To serve as a core, in which the light is guided. Their prime characteristic is a low absorption in the desired wavelength region. The fiber either is a plastic clad pure silica core fiber (PCS) or receives a fused silica cladding with a lower refractive index.
  • To build up a photonic crystal fiber (PCF) preform (stacking of different glass pieces, or drilling holes into the rods)
  • To locally adjust refractive index or stress in fibers. One way to produce polarization-maintaining fibers is to use two stress inducing Boron doped rods.
  • Handles for optical fiber production
High purity fused silica rods

High purity fused silica rods have a low absorption coefficient and are well suited as core material in plastic clad fibers or to be clad by the rod in tube process using jacketing tubes, the cladding service or as a component for photonic crystal fiber preforms. For more details, please check the data sheet or contact our experts.

Rods with a reduced refractive index

These fluorine doped fused silica rods allow you to produce individual preforms or to test new designs by rather simple mechanical or hot processing. The typical size is round with an outer diameter of 1 mm to 50 mm, but custom diameters are available upon request. For more details, please contact our experts.

Fused silica rods are used as a utility in optical fiber production. The first application can be during the deposition, the second during fiber draw.

  • Handles for fused silica production by VAD:
    In the VAD process, the front face of a fused silica rod serves as the deposition target for the soot. For this application the rod needs to have a low content of mobile metallic impurities (especially copper, Lithium, Sodium and Potassium, should be low). Depending on the exact setup of the process, bow and bubble content can be important as well.
  • Handles for fiber draw
    The prefroms used for drawing optical fibers are in most cases very expensive. To reduce the material loss in startup and end phases of the drawing process typically extension rods (so called handles) are used. Most common is the usage at the top of the preform to use it to mount the preform in the fiber-drawing tower to draw the whole preform to the end. Additionally the handle avoids any mechanical damage to the optical fiber preform by the holding unit of the draw tower.

A further application is the lower extension rod. This is typically shorter and smaller. When the preform is heated to melting, a first glass drop drips down, before the stable drawing of the fiber starts. Using a material with similar viscosity as a drop off piece saves original preform material, improving overall yield.

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