Patent Publication Number: US-2015068252-A1

Title: Optical fiber drawing apparatus having simple structure and optical fiber drawing method using the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This U.S. non-provisional patent application claims priority under 35 U.S.C. §119 of Korean Patent Application No. 10-2013-0109161, filed on Sep. 11, 2013, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     The present invention disclosed herein relates to an apparatus and method of manufacturing an optical fiber, and more particularly, to an optical fiber drawing apparatus having a simple structure with a double-heating furnace and an optical fiber drawing method using the same. 
     In general, soft glass fibers may be manufactured through a rod-in tube method in which a core glass rod is firstly inserted in a clad glass tube and then drawn, or through a double crucible method in which core and clad glass rods are melted in double crucibles and then drawn. The double crucible method may make a process of manufacturing optical fibers simple. However, a system constituting the double crucible furnace is very complex. First, the whole double crucible structure should be set to an argon atmosphere. Also, the double crucible has a complex structure, in which a heating furnace should be disposed outside the double crucible, including an auto feeding device supplying core and clad ingots into a double-cylindrical structure, which is divided into a center crucible for core and outer crucible for clad, and a control device for applying a pressure to the inside of the double crucible by using argon gas. After manufacturing the optical fiber, the double crucible has been already contaminated by source glass that has been previously used. Thus, the inside of the double crucible should be treated with chemicals to completely remove the glass adhering to a wall. 
     SUMMARY OF THE INVENTION 
     The present invention provides an optical fiber drawing apparatus having a simple structure and an optical fiber drawing method using the same. 
     The present invention also provides an optical fiber drawing apparatus that is capable of improving productivity and an optical fiber drawing method using the same. 
     Embodiments of the inventive concept provide optical fiber drawing apparatuses including: a crucible accommodating core and clad sources and having a bottom hole through which the core and clad sources pass; and a plug disposed under the crucible, the plug passing through the bottom hole, wherein the plug includes: a bottom plug disposed under the crucible to close the bottom hole; and a first upper plug disposed on the bottom plug to pass through the bottom hole. 
     In some embodiments, the optical fiber drawing apparatuses may further include a second upper plug disposed on the first upper plug, the second upper plug passing through the clad source to extend up to the core source. 
     In other embodiments, the optical fiber drawing apparatuses may further include a plate having a first upper hole aligned with the bottom hole. 
     In still other embodiments, the plate may include a metal or glass. 
     In even other embodiments, the plug may further include a third upper plug disposed on the first upper plug to extend up to the inside of the first upper hole. 
     In yet other embodiments, the optical fiber drawing apparatuses may further include a partition wall protruding from a sidewall within the crucible and having a second upper hole aligned with the bottom hole. 
     In further embodiments, the crucible may include: a lower crucible having the bottom hole; and an upper crucible extending on the lower crucible, wherein the lower crucible may store the clad source, and the upper crucible stores the core source. 
     In still further embodiments, the lower crucible may have a clad injection hole or inert gas injection hole to which the clad source or inert gas is supplied. 
     In even further embodiments, the plug may further include a fourth upper plug disposed on the first upper plug to extend up to the inside of the second upper hole. 
     In yet further embodiments, the optical fiber drawing apparatuses may further include an inner crucible loaded into the inside of the crucible and having a third upper hole aligned with the bottom hole. 
     In much further embodiments, the plug may further include a fifth upper plug disposed on the first upper plug to extend up to the third upper hole. 
     In other embodiments of the inventive concept, optical fiber drawing apparatuses includes: a crucible accommodating core and clad sources and having a bottom hole through which the core and clad sources pass; a plate having a center hole, the plate being disposed between the core source and the clad source in the crucible; and a bottom plug closing the bottom hole of the crucible, wherein the plate includes an upper hole aligned with the bottom hole. 
     In some embodiments, the optical fiber drawing apparatuses may further include an upper plug disposed on the bottom plug to extend up to the upper hole. 
     In still other embodiments of the inventive concept, methods of drawing an optical fiber, the methods including: providing a clad source into a crucible having a bottom hole to which a plug is coupled; providing a core source into a crucible disposed on the clad source; melting the core and clad sources; and separating the plug from the crucible to form an optical fiber comprising a core and clad. 
     In some embodiments, the forming of the optical fiber may include providing an inert gas into the crucible. 
     In other embodiments, the methods may further include providing a plate on the clad source before the core source is provided, wherein the plate may have a first upper hole aligned with the bottom hole. 
     In still embodiments, the clad and core sources may be separated from each other by a partition wall disposed on a side-wall of the crucible, wherein the partition wall may have a second upper hole aligned with the bottom hole. 
     In even embodiments, the crucible may include: a lower crucible disposed under the partition wall to store the clad source; and an upper crucible disposed on the partition wall to extend from the lower crucible and store the core source, wherein the lower crucible may include a clad injection hole or inert gas injection hole to which the clad source or inert gas is supplied. 
     In yet embodiments, the methods may further include an inner crucible loaded on the inside of the crucible to accommodate the core source, wherein the inner crucible may have a third upper hole aligned with the bottom hole. 
     In further embodiments, the plug may include: a bottom plug under the bottom hole; and at least one upper plug passing through the bottom hole to extend up to the core source on the bottom plug, wherein the optical fiber may be drawn when the bottom and upper plugs are separated from the crucible. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the present invention, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the inventive concept and, together with the description, serve to explain principles of the present invention. In the drawings: 
         FIG. 1  is a cross-sectional view of an optical fiber drawing apparatus according to a first embodiment of the inventive concept; 
         FIG. 2  is a cross-sectional view illustrating a state where a crucible and a plug of  FIG. 1  are separated from each other; 
         FIG. 3  is a cross-sectional view of an optical fiber drawing apparatus according to a first application example of the inventive concept; 
         FIG. 4  is a cross-sectional view of an optical fiber drawing apparatus according to a second application example of the present invention; 
         FIG. 5  is a cross-sectional view of an optical fiber drawing apparatus according to a second embodiment of the inventive concept; 
         FIG. 6  is a cross-sectional view illustrating a state where a crucible and a plug of  FIG. 5  are separated from each other; 
         FIG. 7  is a cross-sectional view of an optical fiber drawing apparatus according to a third embodiment of the inventive concept; 
         FIG. 8  is a cross-sectional view illustrating a state where a crucible and a plug of  FIG. 7  are separated from each other; 
         FIG. 9  is a cross-sectional view of an optical fiber drawing apparatus according to a third application example of the inventive concept; 
         FIG. 10  is a cross-sectional view of an optical fiber drawing apparatus according to a fourth embodiment of the inventive concept; and 
         FIG. 11  is a cross-sectional view illustrating a state where a crucible and a plug of  FIG. 9  are separated from each other. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Advantages and features of the present invention, and implementation methods thereof will be clarified through following embodiments described with reference to the accompanying drawings. The present disclosure may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Like reference numerals refer to like elements throughout. 
     In the following description, the technical terms are used only for explain a specific exemplary embodiment while not limiting the present invention. The terms of a singular form may include plural forms unless referred to the contrary. The meaning of “include,” “comprise,” “including,” or “comprising,” specifies a property, a region, a fixed number, a step, a process, an element and/or a component but does not exclude other properties, regions, fixed numbers, steps, processes, elements and/or components. 
     Additionally, the embodiment in the detailed description will be described with sectional views as ideal exemplary views of the present invention. Also, in the figures, the dimensions of layers and regions are exaggerated for clarity of illustration. Accordingly, shapes of the exemplary views may be modified according to manufacturing techniques and/or allowable errors. Therefore, the embodiments of the inventive concept are not limited to the specific shape illustrated in the exemplary views, but may include other shapes that may be created according to manufacturing processes. For example, an etched region illustrated or described as a rectangle will, typically, have rounded or curved features. Areas exemplified in the drawings have general properties, and are used to illustrate a specific shape of a semiconductor package region. Thus, this should not be construed as limited to the scope of the present invention. 
       FIG. 1  is a cross-sectional view of an optical fiber drawing apparatus according to a first embodiment of the inventive concept,  FIG. 2  is a cross-sectional view illustrating a state where a crucible and a plug of  FIG. 1  are separated from each other. 
     Referring to  FIGS. 1 and 2 , the optical fiber drawing apparatus according to the first embodiment of the inventive concept may include the crucible  10  and the plug  50 . The crucible  10  may have a basket shape for accommodating core and clad sources  60  and  70 . According to an example of the invention, the crucible  10  may include a lower crucible  14  storing the clad source  70  and an upper crucible  16  storing the core source  60 . The lower and upper crucibles  14  and  16  may be distinguished according to respective levels or storing positions of the clad and core sources  70  and  60 . The lower crucible  14  may have a bottom hole  12 . The upper crucible  16  may extend upward from the lower crucible  14 . Although not shown, a heater for heating the core and clad sources  60  and  70  may be disposed on an outer wall of the crucible  10 . 
     The plug  50  may block the bottom hole  12  of the crucible  10 . The plug  50  may include a bottom plug  52  and a first upper plug  54 . The bottom plug  52  may have a diameter greater than that of the bottom hole  12  and be disposed under the crucible  10 . The first upper plug  54  may be disposed on the bottom plug  52 . The first upper plug  54  may have the same diameter as that of the bottom hole  12  and be coupled to the inside of the bottom hole  12 . Since the optical fiber drawing apparatus according to the first embodiment of the inventive concept has a simple structure, productivity thereof may be improved. 
     Hereinafter, a method of drawing an optical fiber by using the optical fiber drawing apparatus according to the first embodiment of the inventive concept. 
     First, the clad source  70  is provided in the crucible  10 . The clad source  70  having a sufficient amount to be drawn as an optical fiber  80  may be disposed in the lower crucible  14 . Here, the clad source  70  may be in a solid state. 
     The core source  60  is provided on the clad source  70  in the crucible  10 . The core source  60  may be provided in the upper crucible  16 . The core source  60  may be in a solid state. 
     Then, the crucible  10  may be heated until the core and clad sources  60  and  70  are melted. Here, the core and clad sources  60  and  70  may be melted at temperatures different from each other. According to an example of the inventive concept, the core and clad sources  60  and  70  may be melted in a state where an interface therebetween is maintained. The core and clad sources  60  and  70  may be melted at temperatures different from each other. The core source  60  may have viscosity different from that of the clad source  70 . When the core and clad sources  60  and  70  are melted, a high pressure greater than the normal pressure may be applied into the crucible  10 . 
     The plug  50  may be separated from the crucible  10  to draw the optical fiber  80  from the crucible  10 . An inert gas may be provided in the crucible  10 . The inert gas may have a pressure higher than the atmospheric pressure. The core and clad sources  60  and  70  may be drawn toward a lower side of the crucible  10  through the bottom hole  12  along the plug  50 . For example, the core  62  and clad  72  may be drawn through the bottom hole  12  and then may be thinned in a fiber form. The method of drawing the optical fiber according to the first embodiment of the inventive concept may improve productivity thereof. 
       FIG. 3  is a cross-sectional view of an optical fiber drawing apparatus according to a first application example of the inventive concept. 
     Referring to  FIG. 3 , an optical drawing apparatus according to a first application example of the inventive concept may include a plug  50  comprising a bottom plug  52 , a first upper plug  54 , and a second upper plug  55 . In the first application example, the second upper plug  55  of the first embodiment is added. The second upper plug  55  may have a diameter less than that of the first upper plug  54  and be disposed on the first upper plug  54 . The second upper plug  55  may have a height from the bottom of the lower crucible  14  to the upper crucible  16 . According to an example of the invention, the second upper plug  55  may pass through the clad source  70  within the crucible  10  to extend up to a bottom surface of the core source  60 . The second upper plug  50  may provide a passage from a top surface of the clad source  70  to the bottom hole  12  with respect to the core source  60 . For example, the core  62  may have a diameter different from that of the second upper plug  55 . The clad core  72  may surround a circumference of the core  62 . 
       FIG. 4  is a cross-sectional view of an optical fiber drawing apparatus according to a second application example of the inventive concept. 
     Referring to  FIG. 4 , the optical drawing apparatus according to a second application example of the inventive concept may include a plug  50  having a second upper plug  55  disposed on a bottom plug  52 . The second upper  55  may extend from the inside of the bottom hole  12  to the core source  60 . Here, the second upper plug  55  may extend up to the inside of the core source  60 . The bottom plug  50  may support the clad source  70  within the lower crucible  14 . In the second application example, the first upper plug  54  of the first embodiment is removed. 
       FIG. 5  is a cross-sectional view of an optical fiber drawing apparatus according to a second embodiment of the inventive concept,  FIG. 6  is a cross-sectional view illustrating a state where a crucible and a plug of  FIG. 5  are separated from each other. 
     Referring to  FIGS. 5 and 6 , the optical fiber drawing apparatus according to the second embodiment of the inventive concept may separate a core source  60  from a clad source  70  within a crucible  10  and may include a plate  20  having a first upper hole  22  aligned with a bottom hole  12 . The plate  20  may include a disc having a hole similar with the bottom hole  12  of the crucible  10 . The core and clad sources  60  and  70  may be vertically separated from each other within the crucible  10  by the plate  20 . The clad source  70  may be provided in a lower crucible  14 . The plate  20  may be provided on the clad source  70 . The core source  60  may be provided on the plate  20 . That is, the core source  60  may be loaded in an upper crucible  16 . Then, the core and clad sources  60  and  70  may be heated until the core and clad sources  60  and  70  are melted. The plate  20  may have a heat-resisting property. According to an example of the inventive concept, the plate  20  may include a metal such as a steel use stainless (sus), or glass. As an optical fiber  80  is drawn, the plate  20  may be changed in position depending on a height (a surface level) of the clad source  70 . A first upper hole  22  may have a diameter less than that of the bottom hole  12 . A third upper plug  56  may block the first upper hole  22 . The third upper plug  56  may have the same diameter as that of the first upper hole  22 . However, the present invention is not limited thereto and may have various embodiments. For examples, the third upper plug  56  may be removed, or the third upper plug  56  may have a diameter less than that of the first upper hole  22 . Finally, when the plug  50  and the crucible  10  are separated from each other, the optical fiber  80  may be drawn. n the second embodiment, the optical fiber drawing apparatus includes the plate  20  within the crucible  10  of the first embodiment. 
       FIG. 7  is a cross-sectional view of an optical fiber drawing apparatus according to a third application example of the inventive concept.  FIG. 8  is a cross-sectional view illustrating a state where a crucible and a plug of  FIG. 7  are separated from each other 
     Referring to  FIGS. 7 and 8 , the optical fiber drawing apparatus according to the third embodiment of the inventive concept may include a partition wall  30  having a second upper hole  32  aligned with a bottom hole  12  and protruding from an inner wall of the crucible  10 . The partition wall  30  may separate core and clad sources  60  and  70  in the crucible  10  from each other. According to an example of the inventive concept, the partition wall  30  may extend inward from a boundary between lower and upper crucibles  14  and  16  to the insides of the lower and upper crucibles  14  and  16 . A fourth upper plug  57  have the same diameter as that of the second upper hole  32 . However, the present invention is not limited thereto and may have various embodiments. For example, the fourth upper plug  57  may be removed, or the fourth upper plug  57  may have a diameter less than that of the second upper hole  32  and be inserted into the second upper hole  32 . In the third embodiment, the optical fiber drawing apparatus includes the partition wall  30  disposed on the inner wall of the crucible  10  of the first embodiment. 
       FIG. 9  is a cross-sectional view of an optical fiber drawing apparatus according to a third application example of the inventive concept. 
     Referring to  FIG. 9 , the optical fiber drawing apparatus according to the third application example the present invention may include a clad injection hole  18  between an inner bottom and a partition wall  30  of a lower crucible  14 . The clad injection hole  18  is a pass through which a clad source or inert gas is injected into the lower crucible  14 . The inert gas may include an inactive gas. For example, when the clad source  70  is discharged from a bottom hole  12 , the clad source  70  and the inert gas may be continuously provided into the lower crucible  14  through the clad injection hole  18 . Although not shown, a tube communicating with a clad or gas supply unit (not shown) may be inserted into the clad injection hole  18 . In the third application example, the optical fiber drawing apparatus includes the clad injection hole  18  defined in a sidewall of the lower crucible  14  and the partition wall  30  of the first embodiment. 
       FIG. 10  is a cross-sectional view of an optical fiber drawing apparatus according to a fourth embodiment of the inventive concept,  FIG. 11  is a cross-sectional view illustrating a state where a crucible and a plug of  FIG. 9  are separated from each other. 
     Referring to  FIGS. 10 and 11 , the optical fiber drawing apparatus according to the fourth embodiment of the inventive concept may include an inner crucible  40  disposed in the crucible  10  and having a third upper hole  42  aligned with a bottom hole  12 . A core source  60  may be stored in the inner crucible  40 . A clad source  70  may be disposed under the inner crucible  40 . The inner crucible  40  and the clad source  70  may be stored in the crucible  10 . The third upper hole  42  may have a diameter different from that of the bottom hole  12 . A fifth upper plug  58  may have the same diameter as that of the third upper hole  42 . The present invention is not limited thereto and may have various embodiments. For example, the fifth upper plug  58  may be removed, or the fifth upper plug  58  may have a diameter less than that of the third upper hole  42 . In the fourth embodiment, the optical fiber drawing apparatus includes the inner crucible  40  disposed in the crucible  10  of the first embodiment. 
     As described above, the optical fiber drawing apparatus according to the embodiments of the inventive concept may include the crucible having the simple structure and the plug. The crucible may have a bottom hole. The plug may be coupled to the bottom hole. The clad and core sources may be accommodated or stored in the crucible. The clad and core sources may be disposed in the lower and upper crucibles, respectively. The plug may include the bottom and upper plugs. The bottom plug may seal the bottom hole. The upper plug may pass through the clad to extend up to the core. When the plug is separated from the crucible, the core may pass through the clad and the bottom hole along the upper plug and then be drawn. The core may have the same diameter that of the upper plug. Also, the clad may be drawn out of the crucible through the bottom hole. The clad may surround the circumference of the core. The clad may have the same diameter that of the bottom hole when the fiber is initially drawn. When the plug is separated from the crucible, the optical fiber may be easily formed. 
     Therefore, the optical fiber drawing apparatus and the method using the same according to the embodiments of the inventive concept may improve the productivity. 
     The above-disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments, which fall within the true spirit and scope of the present invention. Thus, to the maximum extent allowed by law, the scope of the present invention is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description. Therefore, the preferred embodiments should be considered in descriptive sense only and not for purposes of limitation.