Halogen doped optical fibers

A method of forming an optical fiber preform, comprising:

• flowing a silicon halide and O2 inside of a substrate tube at a combined partial pressure of from about 5 Torr to about 45 Torr, wherein the silicon halide comprises SiCl4 and wherein a molar ratio of the silicon halide to O2 is greater than 1.5;
• applying energy to form a plasma from the silicon halide and the O2, the plasma heating an inside surface of the substrate tube to a temperature of from about 1000° C. to about 1700° C.;
• and
• depositing silica glass from a reaction of the silicon halide and the O2 on the inside surface of the substrate tube, the silica glass comprising chlorine derived from the silicon halide at a concentration of 2.0 wt % or greater and the silica glass including a relative refractive index greater than 0.06 Δ % per wt % of the chlorine compared to undoped SiO2.

A method of forming an optical fiber;

• comprising:
• flowing a silicon halide and O2 inside of a substrate tube, wherein the silicon halide comprises SiCl4 and wherein a molar ratio of the silicon halide to O2 is greater than 1.5, further wherein a combined partial pressure of the silicon halide and O2 within the substrate tube is from about 5 Torr to about 45 Torr;
• applying energy to form a plasma from the silicon halide and the O2, the plasma heating an inside surface of the substrate tube to a temperature of from about 1000° C. to about 1400° C.;
• and
• depositing silica glass inside the substrate tube from a reaction of the silicon halide and the O2 on the inside surface of the substrate tube, the silica glass comprising chlorine derived from the silicon halide at a concentration of from about 2.0 wt % to about 7.0 wt % and the silica glass including a relative refractive index greater than 0.06 Δ% per wt % of the chlorine compared to undoped SiO2.