1. Assalamuyalikum A K M Borhanice 081-19-831 Md. Nadim hossian 081-19-869 Hayatun-nobe 081-19-8 Group:-4

2. The practical considerations and Drawing of optical fibers

3. Preparation of Optical fibers Melting techniques Vapour-Phase deposition methods

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

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

6. 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 1300 0 C.

7. 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

8. 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.

15. 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 A bait glass rod is dipped into the molten combination and slowly withdrawn giving a composite core-clad preform which may be drawn into a fiber This technique is useful for the production of large core diameter step index-fibers

17. 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 1200 0 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