Abstract: Disclosed is an apparatus for low polarization mode dispersion. The apparatus is operative to draw an optical fiber from a prepared preform using a draw tower and includes (a) a main heating source serving to heat the preform; and, (b) a stationary auxiliary heating source disposed below the main heating source, adjacent to the optical fiber drawn from the preform, for serving to locally and periodically heating the drawn optical fiber so as to remove residual stresses from the optical fiber, thereby minimizing polarization mode dispersion.

Abstract: An optical fiber preform and a fabrication method thereof. In the present invention, an outer OH-barrier and an inner OH-barrier free of P2O5 are deposited respectively between a substrate tube and a cladding layer and between the cladding layer and a core layer during a deposition process. In addition, a refractive index increases toward the center in the core layer.

Abstract: An apparatus and method for manufacturing an optical fiber preform by MCVD is disclosed. In the preform manufacturing apparatus, a cylindrical deposition tube receives a source gas through one end and discharges the source gas through the other end. A first heat source is mounted to a guide and forms a first high temperature area inside the deposition tube by heating the outer circumferential surface of the deposition tube. A second heat source is mounted to the guide, apart from the first heat source by a predetermined distance along the length direction of the deposition tube, and forms a second high temperature area inside the deposition tube by heating the outer circumferential surface of the deposition tube. A beat source mover moves the first and second heat sources, maintaining the distance between the first and second heat sources.

Abstract: Disclosed are an optical fiber preform manufacturing apparatus and method in which processes for shrinking and closing a deposited tube are conducted using a device suitable for those processes, which device is other than the device used in a deposition process for forming the deposited tube on the inner surface of a preform tube, thereby reducing the processing time while reducing the amount of OH penetrated from the preform tube into a vitreous component of the deposited tube, thereby achieving a reduction in OH loss.

Abstract: An apparatus and method for measuring residual stress and photoelastic effect of an optical fiber is disclosed.

Abstract: Disclosed is a system for drawing an optical fiber for controlling polarization mode dispersion. A furnace is provided for uniformly heating an optical fiber preform in the drawing system mounted to an optical fiber draw tower. The furnace comprises: (a) a main body; (b) a sub-body placed coaxially with the main body and having a diameter smaller than that of the main body; and (c) an upper gas feeding section over the main body, wherein the upper gas feeding section includes a first hollow rotary body having at least one slit in the inner surface thereof along the longitudinal direction of an optical fiber and at least one opening extended in the direction of the center, whereby a gas artificially/periodically creates non-contact polarization to the optical fiber by the first hollow rotary body. Effective non-contact control can be carried out about polarization mode dispersion of the optical fiber.

Abstract: Disclosed are an optical fiber perform manufacturing apparatus and method in which processes for shrinking and closing a deposited tube are conducted using a device suitable for those processes, which device is other than the device used in a deposition process for forming the deposited tube on the inner surface of a perform tube, thereby reducing the processing time while reducing the amount of OH penetrated from the perform tube into a vitreous component of the deposited tube, thereby achieving a reduction in OH loss.

Abstract: An apparatus and a method for manufacturing an optical fiber preform by modified chemical vapor deposition (MDVD). The apparatus includes a heating device for heating a rotating substrate tube while moving in a predetermined direction, wherein the heating unit has a first heating unit located at the front with respect to the moving direction, for heating the substrate tube with a relatively low flame pressure, and a second heating unit located at the rear of the first heating means with respect to the moving direction, for heating the substrate tube with a relatively high flame pressure. The first and second heating units are selectively used for deposition and collapsing, such that the duration and temperature of collapsing can be reduced.

Abstract: A cooler of an optical fiber draw tower, situated below a melting furnace for melting a preform for an optical fiber, for cooling the optical fiber drawn from the preform melted in the melting furnace, includes at least one heat exchanger installed with a predetermined length surrounding the optical fiber drawn from the melting furnace, for cooling the drawn optical fiber. The heat exchanger is formed of a thermoelectric cooler (TEC) for taking electrical energy through one heat absorbing surface to emit heat to the other heat emitting surface and has a tubular shape in which the heat absorbing surface of the TEC surrounds the optical fiber drawn from the melting furnace along the drawing direction by a predetermined length, and the drawn optical fiber is cooled as it passes through the tubular TEC. Also, the cooler further includes an auxiliary cooler attached to the heat emitting surface of the TEC, for cooling the emitted heat.

Abstract: An optical fiber preform having a substrate tube, a cladding layer and a core layer further includes a first barrier layer deposited by a material having a low OH diffusion coefficient between the substrate tube and the cladding layer, wherein the first barrier layer is for substantially preventing OH contained in the substrate tube from being diffused into the cladding layer. The optical fiber preform further includes a second barrier layer formed by depositing a material having a low OH diffusion coefficient between the cladding layer and core layer, for substantially preventing OH which has been diffused into the cladding layer from the substrate tube from being diffused further into the core layer.

Abstract: Disclosed is an optical fiber coating device for coating the outer circumference of the optical fiber with the coating material, in which the coating device is provided with and a gas provider for providing an environmental gas within the coating device, and a cooler for cooling down the environmental gas provided to the coater from the gas provider.