The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 21, 2005
Filed:
Feb. 20, 2002
Kazuya Kuwahara, Yokohama, JP;
Katsuya Nagayama, Yokohama, JP;
Ichiro Tsuchiya, Yokohama, JP;
Masashi Onishi, Yokohama, JP;
Kazuya Kuwahara, Yokohama, JP;
Katsuya Nagayama, Yokohama, JP;
Ichiro Tsuchiya, Yokohama, JP;
Masashi Onishi, Yokohama, JP;
Sumitomo Electric Industries, Ltd., Osaka, JP;
Abstract
The drawing method of the present invention uses a drawing furnace comprising a furnace muffle tube, a furnace body and a heater. According to the method, an optical fiber preform is inserted from the inlet of the furnace muffle tube, the optical fiber preform is melted by means of a heater, under a specified gas atmosphere, and is drawn toward the outlet of the furnace muffle tube by means of a specified drawing tension. The optical fiber preform and the drawing furnace used in this method both satisfy the condition of below-indicated formula (1):≧8  (1)wherein L indicates the length of the furnace body in the drawing direction and D indicates the diameter of the optical fiber preform. Through this method, even for the case of drawing optical fibers having a large relative index difference between the central core and the cladding, optical fibers wherein residual amounts of lattice defects are sufficiently reduced and degradation of characteristics under a hydrogen atmosphere is sufficiently suppressed can be obtained efficiently and at low cost.