Assalamuyalikum A K M Borhanice Md. Nadim hossian Hayatun-nobe Group:-4

The practical considerations and Drawing of optical fibers

Preparation of Optical fibers Melting techniques Vapour-Phase deposition methods

Melting techniques 1.Ultra pure material powders are preparing 2.Made a bubble free multi component glass

Ultra pure material powders are These powders are very high level of purify. Filtration Coprecipiation

Made a bubble free multi component glass The highly pure powdered low melting glass material is melted to a bubble free multi component glass. The change in refractive index is achieved by either a change in composition of various constituents. The melting of these multi component glass systems occur at relatively low temperatures between 900 and C.

Silica crucibles can give dissolution into the melt which may introduce inhomogenities into the glass,especially at high melting temperatures A technique to avoid this problem is to melt the glass directly into a radio frequency 5MHz induction furnace while cooling the silica by gas or water flow

Technique-01 The traditional technique for fine optical fiber waveguides is to make a preform using the rod in tube process. A rode of core glass inserted into a tube of cladding glass & the preform is drwan in a vertical muffle furnace as shown in fig 4.3.These technique is very useful for the production of step index fiber with large core and cladding diameter.

In this technique a layer of cladding glass is poured over the core glass in a platinum crucible. A bait glass rod is dipped into the molten combination and slowly withdrawn giving a composite core-clad preform which may be drawn into a fiber This technique is useful for the production of large core diameter step index-fibers

Double crucible Technique In this method core and cladding glass in the form of separate rods is fed into coencetric platinum crucibles The assembly is located in a muffle furnace capable of heating the crucible contents between the temperature 800 and C. The crucibles have nozzles in their bases from which the clad fiber is drawn directly from the melt It is possible to achieve a reasonable refractive index (graded index) via this diffusion process