摘要:
A drawing apparatus 1 comprises a drawing furnace 11, a heating furnace 21, and a resin curing section 31. An optical fiber 3 drawn upon heating in the drawing furnace 11 is sent to a heating furnace 21, where a predetermined part of the optical fiber 3 is annealed at a predetermined cooling rate. The temperature of a heater 22 of the heating furnace 21 at the furnace center is set to a temperature within the range from 1200 to 1600° C. Thereafter, the optical fiber 3 is coated with a UV resin liquid 52 by a coating die 51, and the UV resin 52 is cured in the resin curing section 31, so as to yield a coated optical fiber 4.
摘要:
An optical fiber preform 2 having a viscosity ratio R&eegr;=&eegr;0/&eegr;t of 2.5 or less between the core average viscosity &eegr;0 and the total average viscosity &eegr;t is prepared, and is drawn by a drawing furnace 11 so as to yield an optical fiber 3, which is then heated to a temperature within a predetermined range so as to be annealed by a heating furnace 21 disposed downstream the drawing furnace 11. Here, upon annealing in the heating furnace 21, the fictive temperature Tf within the optical fiber lowers, thereby reducing the Rayleigh scattering loss. At the same time, the viscosity ratio condition of R&eegr;≦2.5 restrains the stress from being concentrated into the core, thereby lowering the occurrence of structural asymmetry loss and the like. Hence, an optical fiber which can reduce the transmission loss caused by the Rayleigh scattering loss and the like as a whole, and a method of making the same can be obtained.
摘要:
A drawing apparatus 1 has a drawing furnace 11, a heating furnace 21, and a resin curing section 31. The drawing furnace 11 has a muffle tube 13 to which an He gas supply passage 15 from an He gas supply section 14 is connected so as to supply He gas. The optical fiber 3 drawn upon heating by the drawing furnace 11 is fed to the heating furnace 21, whereby a predetermined part of the optical fiber 3 is annealed at a predetermined cooling rate. The heating furnace 21 has a muffle tube 23 to which an N2 gas supply passage 25 from an N2 gas supply section 24 is connected so as to supply N2 gas. Thereafter, the optical fiber 3 is coated with a UV resin 39 by a coating die 38, and the UV resin 39 is cured in the resin curing section 31, whereby a coated optical fiber 4 is formed.
摘要:
A drawing apparatus 1 comprises a drawing furnace 11, a protecting tube 21, and a resin curing unit 31. A buffer chamber 41 is disposed between the drawing furnace 11 and the protecting tube 21, and has a length L1 in the drawing direction of the optical fiber 3. The buffer chamber 41 is constituted by a first buffer cell 42 and a second buffer cell 45. In the space within the buffer chamber 41, an He gas, which is an atmosphere gas within the drawing furnace 11, and the air, which is an atmosphere gas within the protecting tube 21, exist in a mixed state. The optical fiber 3 drawn upon heating in the drawing furnace 11 is fed to the protecting tube 21, and a predetermined part of the optical fiber 3 is annealed at a predetermined cooling rate. Thereafter, a coating die 62 coats the optical fiber 3 with a UV resin solution 63, and the resin curing unit 31 cures the UV resin 63, whereby a coated optical fiber 4 is obtained.
摘要:
A fiber drawing method according to the present invention is a drawing method of optical fiber for drawing an optical fiber 14 from one end of a fiber preform 13 by softening with heat, wherein the fiber preform 13 is set in a semi-closed space 10, 20 opening in part at a lower end in a fiber drawing furnace, the fiber preform 13 is heated by a heater 15 disposed on the lower end side of this semi-closed space 10, 20, and fiber drawing is carried out with adjusting a quantity of heat dissipation from the upper portion 20 of this semi-closed space.
摘要:
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): L/D≧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.
摘要:
A furnace for drawing an optical fiber provided with a muffle tube (10) and inner tubes (5,5′) connected to the upper end of the core tube, wherein a preform (1) supported by a dummy rod (2) at the upper part thereof is disposed inside the muffle tube (10) and inner tubes (5,5′) so as to be movable downward together with dummy rod (2), the preform (1) is heated and melted by a heater (11) from the outside of the muffle tube (10) and an optical fiber (1a) is pulled out from the lower end of the preform (1); the furnace is further provided with one or a plurality of sets of separating plates (4, 17) adapted to partition a space in the inner tubes (5,5′) above the preform (1) into a plurality of portions in the advance direction of the preform and disposed in the space, and with gas blowing inlets (8) disposed in the parts of wall surfaces of the inner tubes (5,5′) which are below the separating plates (4, 17) and adapted to blow an inert gas into the inner tubes (5,5′) and the muffle tube (10), thereby preventing variations in diameter of the optical fiber (1a).
摘要:
A furnace for drawing an optical fiber provided with a muffle tube (10) and inner tubes (5,5′) connected to the upper end of the core tube, wherein a preform (1) supported by a dummy rod (2) at the upper part thereof is disposed inside the muffle tube (10) and inner tubes (5,5′) so as to be movable downward together with dummy rod (2), the preform (1) is heated and melted by a heater (11) from the outside of the muffle tube (10) and an optical fiber (1a) is pulled out from the lower end of the preform (1); the furnace is further provided with one or a plurality of sets of separating plates (4, 17) adapted to partition a space in the inner tubes (5, 5′) above the preform (1) into a plurality of portions in the advance direction of the preform and disposed in the space, and with gas blowing inlets (8) disposed in the parts of wall surfaces of the inner tubes (5, 5′) which are below the separating plates (4,17) and adapted to blow an inert gas into the inner tubes (5,5′) and the muffle tube (10), thereby preventing variations in diameter of the optical fiber (1a).
摘要:
The present invention provides an optical fiber and the like comprising a structure making it possible to realize optical communications with a higher speed and a larger capacity as compared with conventional optical transmission systems. The optical fiber according to the present invention is an optical fiber in which at least one first portion having a positive chromatic dispersion at a predetermined wavelength within a wavelength band in use and at least one second portion having a negative chromatic dispersion at the predetermined wavelength are arranged adjacent each other along the longitudinal direction thereof. In particular, the optical fiber comprises a polarization coupling structure for inducing coupling between polarization modes of propagating light. This polarization coupling structure randomly causes coupling between polarization modes of the propagating light, whereby polarization mode dispersion decreases at the predetermined wavelength. As a consequence, transmission characteristics are effectively restrained from deteriorating due to polarization mode dispersion. Specifically, the polarization coupling structure is a twist applied to the optical fiber.
摘要:
The amount of dimming components originating in an ultraviolet-curing resin and adhering to a quartz tube is reduced, and a decline in the ultraviolet transmittance is prevented, during ultraviolet-curing of a resin coated on a liner body through an ultraviolet-transmitting tubular member placed inside a curing apparatus and of curing ultraviolet-curing resin by irradiating ultraviolet rays from outside the ultraviolet-transmitting tubular member. Embodiments include coating the inner surface of the ultraviolet-transmitting tubular member with titanium and employing an atmosphere of lover 0.1% oxygen.