Heater having multi hot-zones, furnace having the heater for drawing down optical fiber preform into optical fiber, and method for drawing optical fiber using the same

A furnace for drawing an optical fiber, the furnace comprising:

• a furnace body having an top opening through which an optical fiber preform is introduced and a bottom opening through which an optical fiber drawn from the preform is discharged;
• a gas supply means for flowing an inert gas into a furnace body to maintain the inside of the furnace body under an inert gas atmosphere;
• and
• a heating means installed inside the furnace body and heating the optical fiber preform to draw an optical fiber,
• wherein the heating means includes:
• a first heating unit for heating a preform at a temperature suitable for drawing an optical fiber from the preform;
• and
• a second heating unit for heating a surface of the preform to a relatively lower temperature than the first heating unit,
• wherein the first heating unit is arranged in a neck-down region of the preform, and the second heating unit is arranged above the neck-down region.

A method for drawing an optical fiber by melting a preform in a furnace that includes an electric resistance heater made of graphite or carbon material, the electric resistance heater including:

• a first heating unit for heating a preform at a temperature suitable for drawing an optical fiber from the preform;
• and
• a second heating unit for heating a surface of the preform to a relatively lower temperature than the first heating unit,
• wherein the method comprises:
• (a) supplying a preform into the inside of the furnace;
• (b) arranging the preform and the heater so that a neck-down region of the preform corresponds to the first heating unit and an upper part of the neck-down region of the preform corresponds to the second heating unit;
• (c) applying power to the heater such that the first heating unit and the second heating unit generate heat at different temperatures;
• (d) drawing an optical fiber by heating a surface of the preform arranged in the neck-down region to a first temperature;
• and
• (e) heating a surface of the preform arranged above the neck-down region to a second temperature lower than the first temperature.