j-FST – Fluorine Doped Silica Tubes

The perfect material for individual preform designs and innovative specialty fiber making

j-plasma FST Fluorine Doped Silica Tubes offering has been developed to provide advanced specialty fiber making with the ideal material that precisely meets preform parameters or specialty fiber specifications.

j-FST tubes feature highest fluorine concentrations of 4 weight % resulting in a negative refraction index delta of (17 ± 3) x 10^-3. Their Numerical Aperture (NA) of up to 0.22, relative to pure silica, gives specialty fiber manufactures a reliable source for high performance fluorine doped tubes.

We offer j-FST Fluorine Doped Silica Tubes as uniformly fluorine doped tubes or in customized versions.

Characteristics (uniformly doped tubes)

	Spec.Values	Unit
Material composition	SiO2/F
Fluorine content	up to 4	wt %
Refractive index delta (negative related to undoped silica)	up to (17+/-3)x10-3
Refractive index @ 633nm Refractive index @ 1064	1.440 1.433
Thermal expansion coefficient (20°C-400°C)	2.5x10-7K-1
Density	2.180	g/cm3
Tube inner diameter (I.D.)	20-40	mm
Fluorine doped wall thickness (W.S)	1.5 - 15	mm
Tube length	up to 1.000	mm
Ovality	≤ 3	%
Bow	≤ 1.5	mm/m

 

Applications

Developed for manufacturing of special fiber designs as substrate or jacketing tube, j-FST tubes are the ideal material for:

• Overcladding processes in preform manufacturing
• As substrate materials in MCVD processes
• As fluorine doped capillaries used for specialty fiber designs

Features

• Uniformly high fluorine concentration
• Easy to post-treat and process into preforms or capillaries
• Available with low OH content (less than 20ppm)

Customized tube designs

Customized j-FST tube designs can be individually specified with double or multi step refraction index profiles. Options are:

• Customized wall size dimensions
• Doped and undoped layers in accordance with customer requirements
• Customer-specific fluorine doping concentration
• Inside and/or Outside layers with pure silica

Process Method

The j-FST tubes are manufactured by j-plasma’s Plasma Based Deposition (PBD) process. A plasma torch is thereby used as a heating source for the chemical reaction of SiCl₄, O₂ and a fluorine containing gas. The high temperature plasma leads to chemical deposition conditions that support a high fluorine concentration in the deposited silica layers.