The materials used for the core and the cladding of the IRguide fibers are highly stable heavy metal fluoride glasses (FG). They are made of Zirconium or Hafnium tetrafluoride, associated with fluorides of alkaline, earth alkaline, rare earth and other metals, in various proportions. A typical composition and its characteristics are indicated on the table below.
Zirconium fluoride glass characteristics (typical) |
|
| Composition (mole %) | ZrF4 (57), BaF2 (34), LaF3 (5), AlF3 (4) |
| Glass transition temperature (Tg) | 300°C
|
| Melting temperature | 550°C |
| Linear expansion coefficient | 16 10-6 K-1
|
| Refractive index (nd) | 1,519 |
| Transmission (50 % over 2-mm) | [0.22 - 7.8 µm] |
| Temperature coefficient ([dn/dt) | -1 10-5 K-1
|
The IRguide® fluoride glass infrared fibers are pulled from high-grade fluoride glass preforms. The guiding structure is given by the difference between the index of refraction of the fluoride glass core and of the fluoride glass cladding. Since both core and cladding materials belong to the same fluoride glass family, their interface is very smooth resulting in very low attenuation level.
To respond to the needs of the industry, LeVF offers several brands of Fluoride Glass Fibers labeled IRguide-1, IRguide-2, . respectively, depending on their optical, mechanical and thermal properties.
Specially designed coatings and protections, allow the IRguide fluoride glass infrared fibers to be used in the most severe environments.
