Cane-in-tube method for optical fiber fabrications

Cane-in-tube method for optical fiber fabrications

Microstructured optical fibers (MOFs) can be made entirely from one type of glass as they do not rely on dopants for guidance. MOFs include mainly two type of fibers: (1) Holey fibers, in which the core is solid and light is guided by a modified form of total internal reflection as the air holes lower the effective refractive index of the cladding relative to that of the solid core. (2) Photonic band-gap fibers, in which guidance in a hollow core can be achieved via photonic band-gap effects. [www.orc.soton.ac.uk, Advanced Fibre Technologies & Applications Group].

[Image from Max Planck Institute, Photonics & New Materials, http://www.mpl.mpg.de]

To fabricate MOFs, capillaries need to be drawn (or can be purchased, but material purities varies, depends on the suppliers) first. Those capillaries then stacked as a preform (normally hexagonal mesh structure). The preform will then be caned down to smaller diameter and finally be slotted into a prepared tube (outer cladding). A typically less than 200 µm fiber will be drawn from the final preform.

Cane-in-tube method is also used for other structures such as fiber with suspended core [Monro, Progress in Microstructured Optical Fibers, Annu. Rev. Mater. Res 2006. 36. 467-95]; and for different materials (other compound glasses, lead silicate or Chalcogenide glasses [Lian,zhenggang Solid Microstructured Chalcogenide Glass Optical Fibers for the Near- and Mid-Infrared Spectral Regions, IEEE PTL, Vol.21, No. 24, 1804-1806, 2009]).