Process for fabrication of ytterbium doped optical fiber

A process for fabrication of ytterbium (Yb) doped optical fiber through vapor phase doping technique, said process comprising the steps of:

• depositing pure silica cladding layers inside a silica glass substrate tube at a temperature in the range of 1900 to 1980° C. using MCVD process;
• (ii) sublimating AlCl3 and Yb(thd)3 in their respective sublimator chamber at a temperature in the range of 100 to 170° C. and 180 to 260° C. respectively to obtain Al-precursors and Yb-precursors;
• (iii) introducing preheated Helium in the sublimator chamber of step (ii) at a flow rate in the range of 10 to 50 sccm for Al precursors and 100 to 300 sccm for Yb precursors;
• (iv) transporting Al and Yb precursors with Helium obtained in step (iii) to the substrate tube with the adjustment of temperature of a ribbon burner in the range of 180-370° C.;
• (v) passing O2 gas into a SiCl4 bubbler at a temperature in the range of 15 to 40° C. and a flow rate in the range of 80 to 150 sccm to transport SiCl4—O2 gas mixture to the substrate tube;
• (vi) mixing SiCl4, O2, Al precursors, Yb-precursors, and Helium in the substrate tube followed by concurrent oxidation to form SiO2, Al2O3 and Yb2O3;
• (vii) depositing a sintered core layer comprising SiO2—Al2O3—Yb2O3 with targeted Al2O3 and Yb2O3 concentrations to obtain a deposited tube;
• (viii) collapsing the deposited tube at a temperature in the range of 1900 to 2300° C. to obtain a fabricated preform;
• and
• (ix) drawing fibers from the fabricated preform obtained in step (viii) to obtain ytterbium (Yb) doped optical fiber.