• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    An optical fiber preform includes a silica glass core portion, and a sheath portion surrounding the core portion, the sheath portion being made of a fluorine-containing silica glass having a lower refractive index. the core portion, the core portion comprising a first region that does not include the central axis thereof, the first region containing a first dopant selected from sodium, potassium, and compounds of those a second region which includes the central axis, the second region containing a second dopant which reduces the viscosity of the silica glass, the second dopant having a diffusion coefficient of 1 x 10-12 cm 2 / s or higher and lower to the first dopant at 2000 ° C to 2300 ° C, wherein the entire core portion has a first dopant average concentration of 10 atomic ppm or greater and 2000 atomic ppm or less and a second average concentration doping of 10 atomic ppm e or higher.
    公开号:FR3068907A1
    申请号:FR1856375
    申请日:2018-07-11
    公开日:2019-01-18
    发明作者:Keisei Morita；Yoshiaki Tamura；Hirotaka Sakuma
    申请人:Sumitomo Electric Industries Ltd；
    IPC主号:
    专利说明:

    BACKGROUND OF THE INVENTION
    Field of the Invention The present invention relates to an optical fiber preform.
    Description of related art.
    As optical fibers with a low Rayleigh scattering loss and a low attenuation, silica-based optical fibers each having a core containing an element of alkali metal are known (see, for example, in Japanese patent application published before examination No. 2005-537210, publication of US patent application No. 2006/0130530, Japanese patent application published before examination No. 2009-541796, Japanese patent application published before examination No. 2012-229150, and the Japanese patent application published before examination No. 2016-210632). Incorporation of an alkali metal element into a core portion of an optical fiber preform can reduce the viscosity of the core portion when the optical fiber preform is stretched, thereby standardizing the network structure of a silica glass to reduce the Rayleigh diffusion loss due to the fluctuation of the structure.
    [0003] A diffusion method is known as a method for adding an element of alkali metal to a silica glass. The diffusion method is a method in which an alkali metal element is diffused and added to the inner surface of a glass pipe by heating the glass pipe with an external heat source or by generating a plasma in the glass pipe while vapor from a source material such as the alkali metal element or an alkali metal salt is introduced into the glass pipe.
    [0004] After the alkali metal element is added in the vicinity of the internal surface portion of the glass pipe in the above manner, the glass pipe is reduced in diameter by heating. After the diameter reduction, the inner surface of the glass pipe is etched to a certain thickness in order to remove transition metals such as Ni and Fe inevitably added together with the addition of the element of alkali metal. The diffusion of the alkali metal element is faster than that of the transition metals. Thus, even if the glass surface is etched to a certain thickness to remove the transition metals, the element of alkali metal can be left. After pickling, the glass pipe collapses by heating into a solid core rod containing the alkali metal element. A glass to be formed in a second core portion can be formed on the outer side of the core strip containing the alkali metal element, and the entire core strip and the second core portion can be formed. be used as the core of an optical fiber.
    [0005] A sheath portion having a lower refractive index than the core portion comprising the core rod containing the alkali metal element is formed on the external side of the core portion to produce a preform of optical fiber. The optical fiber preform can be stretched to produce an optical fiber.
    An optical fiber preform described in the Japanese patent application published before examination No. 2016-210632 contains a first dopant (sodium or potassium) in a region comprising the central axis of a core portion, the first dopant having a high diffusion coefficient, and a second dopant in a region which does not include the central axis of the core portion, the second dopant (for example Rb, Cs, Mg, Ca, or Sr) having a low diffusion coefficient. In the Japanese patent application published before examination No. 2016-210632, when an optical fiber is produced by stretching the optical fiber preform, the first dopant and the second dopant are diffused by heating during stretching to standardize the distribution of concentration of alkali metal elements in the core of the optical fiber, thereby resulting in an optical fiber having low attenuation.
    SUMMARY OF THE INVENTION An object of the present invention is to provide an optical fiber preform from which an optical fiber having lower attenuation can be provided.
    One aspect of the present invention provides an optical fiber preform comprising a core portion consisting of a silica glass and a sheath portion surrounding the core portion, the sheath portion consisting of a glass of fluorine-containing silica having a lower refractive index than the core portion, the core portion comprising a first region which does not include a central axis of the core portion, the first region containing a first dopant selected from sodium, potassium, and compounds thereof, and a second region which includes the central axis of the core portion, the second region containing a second dopant which reduces the viscosity of the silica glass, the second dopant having a diffusion coefficient of 1 x 10 12 cm 2 / s or higher and lower than the first dopant at a temperature of 2000 ° C to 2300 ° C, wherein the entire core portion has an average concentration first dopant of 10 ppm atom ic or greater and 2,000 atomic ppm or less, and the entire core portion has an average second dopant concentration of 10 atomic ppm or greater. The term atomic ppm used here indicates the number of dopant atoms in 100 million units of S1O2.
    In the optical fiber preform according to the aspect of the present invention, the second dopant can be any one chosen from Rb, Cs, Mg, Ca, and Sr. The first dopant has a peak concentration at a radius rl in the core portion and the core portion has an external radius r2, and the ratio (r2 / rl) is in the range of 3 to 9.5. The whole core portion can have an average Cl concentration of 10 atomic ppm or higher and of 10,000 atomic ppm or lower.
    BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a conceptual diagram of an optical fiber preform according to an embodiment of the present invention.
    FIG. 2 is a graph illustrating a concentration distribution by doping in a core portion of an embodiment of the optical fiber preform illustrated in FIG. 1.
    FIG. 3 is a graph illustrating a concentration distribution by doping in the core of an optical fiber formed by stretching the optical fiber preform illustrated in FIG. 1.
    Figure 4 is a table that lists the diffusion coefficients of sodium, potassium, cesium, and calcium.
    Figure 5 is a graph illustrating the relationship between the attenuation of an optical fiber at a wavelength of 1550 nm and the average concentration of a first dopant in the entire core portion of a preform fiber optic.
    Figure 6 is a graph illustrating the relationship between the attenuation of an optical fiber at a wavelength of 1550 nm and the average concentration of Cl in the entire core portion of a fiber preform optical.
    Figure 7 is a diagram illustrating an example of steps in the production of an optical fiber preform according to an embodiment of the present invention and an optical fiber.
    Figure 8 is a graph illustrating the relationship between the attenuation of an optical fiber at a wavelength of 1550 nm and the ratio (r2 / rl) of the radius r2 of a core portion d an optical fiber preform at the peak concentration position rl of a first dopant in the core portion.
    DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described in detail below, with reference to the accompanying drawings. In the drawings, the same elements are designated using the same reference signs, and a redundant description is not repeated. The present invention is not limited to these embodiments. The present invention is indicated by the appended claims. It intends to include modifications in the field and an equivalent meaning in relation to the field of claims.
    In an optical fiber produced by stretching an optical fiber preform described in the Japanese patent application published before examination No. 2016-210632, an element of alkali metal (first dopant) having a high diffusion coefficient diffuse at the outside of the core to lower the concentration of the alkali metal element in the central portion of the core. In the distribution of light power in fundamental mode propagating through the core of the optical fiber, the power increases with a decreasing distance from the center of the core. Thus, due to a low concentration of the alkali metal element in the central portion of the core where the power of light in fundamental mode is high, a reduction in attenuation is not sufficient.
    In the case where only an element of alkali metal, such as sodium or potassium, having a high diffusion coefficient, is added to the core portion of the optical fiber preform, the heating of the preform of optical fiber at a drawing temperature of 2,000 to 2,300 ° C causes the element of the alkali metal to diffuse outside the core to lower the concentration of the alkali metal element in the core of an optical fiber to be formed. The Rayleigh diffusion coefficient (value A) is therefore not sufficiently reduced, being lacking to sufficiently reduce the attenuation. The value A refers to the coefficient of the first term on the right side in the expression of approximation α = Αλ ' 4 + B, where a represents the loss of light transmitted in the optical fiber, and λ represents the wavelength light.
    In the case where only the alkali metal element having a high diffusion coefficient is added to the core portion of the optical fiber preform, the peak concentration of alkali metal element in the core portion of the optical fiber preform must be increased in order to maintain a sufficient concentration of alkali metal element in the core of a drawn optical fiber. In this case, unfortunately, a difficulty lies in the drawing of the preform into a fiber due to the crystallization during drawing.
    In the case where only an alkali metal element or an alkaline earth metal element, such as Rb, Cs, Mg, Ca, or Sr, having a low diffusion coefficient is added to the core portion of the optical fiber preform, even if the optical fiber preform is heated to a drawing temperature of 2000 ° C to 2300 ° C, the alkali metal element or the alkaline earth metal element does not diffuse in the whole soul of an optical fiber. Also in this case, the value A is not sufficiently reduced, thus failing to reduce the attenuation sufficiently.
    As with the optical fiber preform described in the Japanese patent application published before examination No. 2016-210632, in the case where a region of a core portion comprising the central axis of the core portion contains a first dopant having a high diffusion coefficient and where a region of the core portion which does not include the central axis contains a second dopant having a low diffusion coefficient, an optical fiber formed by stretching the preform of optical fiber has a low concentration of an alkali metal element in the central portion of its core where the light power in fundamental mode is high. Reducing the attenuation is therefore not sufficient.
    An optical fiber formed by stretching an optical fiber preform according to an embodiment of the present invention described below has a high concentration of an alkali metal element or alkaline earth metal element in the central portion of its soul where the light power in fundamental mode is high and has a sufficiently low attenuation.
    Figure 1 is a conceptual drawing illustrating an optical fiber preform 1 according to an embodiment of the present invention. The optical fiber preform 1 includes a core portion 2 consisting of a silica glass and a sheath portion 3 surrounding the core portion 2, the sheath portion 3 consisting of a silica glass. The core portion 2 contains a first dopant and a second dopant which reduce the viscosity of the silica glass. The sheath portion 3 has a lower refractive index than the core portion 2 and contains fluorine.
    FIG. 2 is a graph illustrating a concentration distribution by doping in the core portion 2 of the optical fiber preform 1. The horizontal axis of FIG. 2 represents a distance from the center of the core portion 2 in a radial direction, the distance being normalized with respect to the radius of the core portion 2 of the optical fiber preform.
    The first dopant is chosen from sodium, potassium and compounds thereof and is contained in a first region of the core portion 2 which does not include the central axis of the core portion 2. The whole core portion 2 has an average first dopant concentration of 10 atomic ppm or higher and of 2000 atomic ppm or lower.
    [0028] The second dopant is contained within a second region of the core portion 2 including the central axis of the core portion 2. The second dopant has a diffusion coefficient of 1 χ 10 '12 cm 2 / s or higher and lower than the first dopant at a heating temperature of 2000 ° C to 2300 ° C during stretching. The entire core portion 2 has an average concentration of second dopant of 10 atomic ppm or higher.
    The whole core portion 2 preferably has an average Cl concentration of 10 atomic ppm or higher and of 10,000 atomic ppm or lower. The second dopant is preferably any one chosen from Rb, Cs, Mg, Ca, and Sr.
    The first region (that is to say, the region which does not include the central axis of the core portion 2) containing the first dopant and the second region (which region which includes the axis central of the core portion 2) containing the second dopant can overlap each other. Preferably, these regions do not overlap each other. In the latter case, no region containing both the first dopant and the second dopant is present. In the latter case, the optical fiber preform is more easily produced.
    Figure 8 is a graph illustrating the relationship between the attenuation of an optical fiber at a wavelength of 1550 nm and the ratio (r2 / rl) of the radius r2 of a portion of core d an optical fiber preform at the peak concentration position rl of a first dopant in the core portion. As is clear from the graph, in the case where r2 / rl is less than 3, most of the first dopant diffuses outside the core by heating in a stretching step to reduce the effect mitigation reduction. In the case where r2 / rl is greater than
    9.5, even if the first dopant diffuses by heating in the stretching step, the first dopant does not extend from one end to the other of the core, thus lowering the effect of reduction of attenuation . Consequently, the ratio (r2 / rl) of the radius r2 of the core portion to the peak concentration position rl of the first dopant in the core portion of the optical fiber preform is preferably in the interval from 3 to
    9.5.
    FIG. 3 is a graph illustrating a concentration distribution by doping in the core of an optical fiber formed by stretching the optical fiber preform 1. The horizontal axis of FIG. 3 shows a distance from the center of the core of the optical fiber in a radial direction, the distance being normalized with respect to the radius of the core of the optical fiber.
    The first dopant having a high diffusion coefficient diffuses into the core center and outside the core by heating during stretching and is thus distributed over a wide interval from the core center to a region outside the core of the optical fiber. In the distribution of first dopant concentration in the optical fiber, although the minimum value of the first dopant concentration can be obtained in the core center, the concentration of first dopant can increase with a decreasing distance from the center lady.
    On the contrary, the second dopant having a low diffusion coefficient diffuses less by heating during stretching. The distribution of concentration in second dopant in the optical fiber is thus in the core, and the concentration increases with a decreasing distance from the center of core.
    The concentration distribution of dopants (the first dopant + the second dopant) in the optical fiber extends over a wide interval from the core center to the region outside the core in the fiber optical, and the concentration increases with a decreasing distance from the center of the soul. The concentration distribution of dopants is an approximation of the distribution of light power in fundamental mode in the optical fiber. As the dopant concentration is high in the central core portion where the light power in fundamental mode is high, a sufficiently low attenuation of the optical fiber can be provided.
    Figure 4 is a table that lists the diffusion coefficients of sodium, potassium, cesium, and calcium. The table presents the diffusion coefficients at 2200 ° C calculated by molecular dynamic simulation. Sodium or potassium is used as the first dopant. Cesium or calcium is used as the second dopant.
    Figure 5 is a graph illustrating the relationship between the attenuation of an optical fiber at a wavelength of 1550 nm and the average concentration of the first dopant in the entire core portion of a preform fiber optic. As is clear from the graph, when the average first dopant concentration in the entire core portion of the optical fiber preform is 10 atomic ppm or greater, the attenuation of the optical fiber at a wavelength of 1,550 nm is 0.16 dB / km or less. When the average concentration of the first dopant in the entire core portion of the optical fiber preform is greater than 2,000 atomic ppm, the preform is easily crystallized, making it difficult to form the preform into a fiber. Therefore, the average concentration of first dopant is preferably 2000 atomic ppm or less.
    Figure 6 is a graph illustrating the relationship between the attenuation of an optical fiber at a wavelength of 1550 nm and the average concentration of Cl in the entire core portion of a fiber preform optical. As is clear from the graph, when the average Cl concentration in the entire core portion of the optical fiber preform is 10 atomic ppm or greater, the attenuation of the optical fiber at a wavelength of 1,550 nm is 0.16 dB / km or less. When the average Cl concentration in the entire core portion of the optical fiber preform is greater than 10,000 atomic ppm, the preform is easily crystallized, making it difficult to form the preform into a fiber. The average Cl concentration is therefore preferably 10,000 atomic ppm or less.
    Figure 7 is a diagram illustrating an example of steps in the production of an optical fiber preform according to an embodiment of the present invention and an optical fiber. Examples of conditions in the steps are also described below.
    In a supply step (step SI), there is provided a glass pipe based on silica in which the first dopant must be diffused. The silica-based glass pipe contains from 100 to 1,000 atomic ppm of chlorine (Cl) and from 6,000 to 10,000 atomic ppm of fluorine, and contains other dopants and impurities in a concentration of 10 ppm by mole or lower. The silica-based glass pipe has an external diameter of approximately 35 mm and an internal diameter of approximately 20 mm.
    In an addition step (step S2), potassium serving as the first dopant is added to the internal surface of the silica-based glass pipe. Potassium bromide (KBr) is used as a source material. The source material is heated to 900 ° C to 1000 ° C with a heat source to generate the source material vapor. The silica glass pipe is heated from the outside with an oxyhydrogen torch so as to have an external surface temperature of 2,100 ° C to 2,200 ° C while the vapor of source material is introduced into the silica-based glass pipe with an oxygen-carrying gas introduced into it at a flow rate of 1 SLM (1 L / min in terms of the standard state). At this point, heating is carried out over a total of 15 turns by passing through the torch at a speed of 40 to 60 mm / min, thereby adding potassium to the internal surface of the silica-based glass pipe by diffusion.
    In a diameter reduction step (step S3), the glass pipe based on silica doped with potassium is reduced in diameter. The silica glass pipe is heated with an external heat source to present an external surface temperature of 2200 ° C to 2300 ° C while oxygen is allowed to flow through the inside the silica-based glass pipe at a flow rate of 0.5 SLM. Passing through the external heat source, heating is performed for a total of 6 to 10 turns to reduce the diameter until the silica-based glass pipe has an internal diameter of approximately 5 mm.
    In a pickling step (step S4), the internal surface of the silica-based glass pipe is pickled. The silica-based glass pipe is subjected to vapor stripping by heating with the external heat source while a mixture of SF 6 gas (0.2 SLM) and chlorine (0.5 SLM) is introduced into the silica-based glass pipe. This pickles the internal surface of the pipe containing impurities, which have been added to it together with the sprayed dopant, in high concentrations, thereby eliminating the impurities.
    In a rod collapsing step (step S5), a calcium doped rod, produced in advance, having a diameter of 5 mm is inserted into the glass pipe based on silica doped with potassium. The silica glass pipe collapses at a surface temperature of 2200 ° C to 2300 ° C while the absolute pressure in the silica glass pipe is reduced to 97kPa or lower and while a mixture of oxygen gas (0.1 SLM) and He (1 SLM) is introduced into the silica-based glass pipe. The collapsing step provides a core portion (with an external diameter of about 25 mm) formed of a first core portion containing calcium (second dopant) and a second core portion containing potassium (first dopant). A third dopant-free core portion can be provided on the external surface of the second core portion, for example by an external vapor deposition (OVD) method or a collapse method.
    In an elongation and machining step (step S6), the core portion is elongated so as to have a diameter of 24 mm. The peripheral portion of the core portion is further machined such that the core portion has a diameter of 17 mm.
    In a sagging-in-baguette step (step S7), a first sheath portion is disposed on the external side of the core portion. At this point, a rod-sagging method is used in which the core portion is inserted into a silica glass tube doped with fluorine and both are integrated with each other by heating with an external heat source to form a rod. The relative difference in refractive index between the core portion and the first sheath portion is up to 0.34%. The use of the sagging-in-rod method results in sufficiently low water contents of the core portion and of the first sheath portion in the vicinity thereof.
    In an external vapor phase deposition step (OVD) (step S8), the rod formed by integrating the core portion with the first sheath portion is elongated so as to have a predetermined diameter, and a second portion of A fluorine-containing sheath is then formed on the outer side of the wand by the (OVD) process to produce an optical fiber preform.
    In a drawing step (step S9), the optical fiber preform produced by the method for producing an optical fiber preform described above is drawn at a drawing speed of 2300 m / min and a drawing voltage of 0.5 N to provide an optical fiber.
    Measuring the residual stress distribution of the optical fiber produced under the previous conditions revealed that there was a small difference in stress of 5 MPa or less in a region extending from the core center towards the sheath. The resulting optical fiber has an attenuation of 0.160 dB / km or less at a wavelength of 1550 nm.
    权利要求:
    Claims (4)
    [1" id="c-fr-0001]
    1. Fiber optic preform including:
    a core portion consisting of a glass of silica; and a sheath portion surrounding the core portion, the sheath portion consisting of a fluorine-containing silica glass having a lower refractive index than the core portion, the core portion comprising:
    a first region which does not include a central axis of the core portion, the first region containing a first dopant selected from sodium, potassium, and compounds thereof, and a second region which includes the axis of the central core portion, the second region containing a second dopant which reduces the viscosity of silica glass, the second dopant having a diffusion coefficient of 1 x 10 12 cm 2 / s or higher, and lower than the first dopant at a temperature of 2,000 ° C to 2,300 ° C, in which the entire core portion has an average first dopant concentration of 10 atomic ppm or greater and 2,000 atomic ppm or less, and the core portion whole has an average second dopant concentration of 10 atomic ppm or higher.
    [2" id="c-fr-0002]
    2. The optical fiber preform according to claim 1, in which the second dopant is any one chosen from Rb, Cs, Mg, Ca, and Sr.
    [3" id="c-fr-0003]
    3. The optical fiber preform according to claim 1 or 2, in which the first dopant has a peak concentration at a radius rl in the core portion and the core portion has an external radius r2, and a ratio (r2 / rl) is in the range of 3 to 9.5.
    [4" id="c-fr-0004]
    4. The optical fiber preform according to claim 1, in which the whole core portion has an average Cl concentration of 10 atomic ppm or higher, and of 10,000 atomic ppm or lower.
    类似技术:
    公开号 | 公开日 | 专利标题
    FR3068907A1|2019-01-18|OPTICAL FIBER PREFORM
    US9229160B2|2016-01-05|Optical fiber preform, method for producing optical fiber, and optical fiber
    US9411095B2|2016-08-09|Optical-fiber preform and method for manufacturing optical-fiber preform
    FR2899693A1|2007-10-12|SINGLE-MODE OPTICAL FIBER.
    TW552437B|2003-09-11|Method of manufacture of an optical waveguide article including a fluorine-containing zone
    FR2896795A1|2007-08-03|PROCESS FOR PRODUCING AN OPTICAL FIBER PREFORM
    FR2725441A1|1996-04-12|OPTICAL FIBER PREFORM AND MANUFACTURING METHOD THEREOF
    FR2963787A1|2012-02-17|PROCESS FOR PRODUCING AN OPTICAL FIBER PREFORM
    FR2951282A1|2011-04-15|OPTICAL FIBER MONOMODE WITH TRANCHEE ENTERREE
    JP6337509B2|2018-06-06|Optical fiber preform manufacturing method
    US10031282B2|2018-07-24|Optical fiber
    FR2511777A1|1983-02-25|OPTICAL FIBERS WITH SIMPLE POLARIZATION AND PROCESS FOR PRODUCING THESE FIBERS
    EP1249432B1|2004-02-04|Process of manufacturing high capacity optical fibre preforms by MCVD
    RU2271025C2|2006-02-27|Single-mode optical fiber and method of production of single-mode optical fiber
    EP1210751B1|2012-08-15|Cladding-pumped optical fibre and method for making same
    EP1256554B1|2006-03-01|Step index optical fibre with doped core and cladding, preform and manufacturing process for such a fibre
    FR2979997A1|2013-03-15|PROCESS FOR PRODUCING OPTICAL FIBER AND OPTICAL FIBER
    FR2902419A1|2007-12-21|METHOD FOR RECHARGING AN OPTICAL FIBER PREFORM
    FR3080463A1|2019-10-25|Optical fiber
    FR3084073A1|2020-01-24|Reduced attenuation optical fiber containing chlorine
    EP1391435B1|2006-05-17|Microstructured optical fibre preform and process of its manufacture
    EP0524591A1|1993-01-27|Process for manufacturing active optical fibres
    EP2337166B1|2016-11-30|Method for manufacturing a single-mode optical fibre with rare-earth-doped core and single-mode optical fibre with rare-earth-doped core
    FR2861719A1|2005-05-06|Fabrication of a preformer with an optimized cone for entry into a fibre optic drawing installation
    JP2008020796A|2008-01-31|Image fiber and optical fiber preform for same
    同族专利:
    公开号 | 公开日
    JP2019019013A|2019-02-07|
    GB2565645A|2019-02-20|
    CN109250898A|2019-01-22|
    GB201811139D0|2018-08-22|
    US20190016630A1|2019-01-17|
    US10723650B2|2020-07-28|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US20040057692A1|2002-08-28|2004-03-25|Ball Laura J.|Low loss optical fiber and method for making same|
    JP2007504080A|2003-08-29|2007-03-01|コーニングインコーポレイテッド|Optical fiber containing alkali metal oxide and method and apparatus for manufacturing the same|
    US20060130530A1|2004-12-21|2006-06-22|Anderson James G|Method of doping silica glass with an alkali metal, and optical fiber precursor formed therefrom|
    US7536076B2|2006-06-21|2009-05-19|Corning Incorporated|Optical fiber containing alkali metal oxide|
    JP5974488B2|2011-04-15|2016-08-23|住友電気工業株式会社|Optical fiber and optical fiber preform|
    JP6551109B2|2014-11-20|2019-07-31|住友電気工業株式会社|Optical fiber|
    JP6613604B2|2015-04-30|2019-12-04|住友電気工業株式会社|Optical fiber preform|US11161767B2|2018-01-25|2021-11-02|Ofs Fitel, Llc|Viscocity-reducing dopants in optical fibers|
    JP2019191297A|2018-04-20|2019-10-31|住友電気工業株式会社|Optical fiber|
    CN111755077A|2020-07-07|2020-10-09|哈尔滨工业大学|Molecular dynamics diffusion simulation method for Fe-Cu and Fe-Ni binary system in high-nitrogen steel high-temperature brazing process|
    法律状态:
    2019-07-24| PLFP| Fee payment|Year of fee payment: 2 |
    2020-09-11| PLSC| Publication of the preliminary search report|Effective date: 20200911 |
    2021-04-09| ST| Notification of lapse|Effective date: 20210305 |
    优先权:
    申请号 | 申请日 | 专利标题
    JP2017136315A|JP7013697B2|2017-07-12|Optical fiber base material|
    JP2017136315|2017-07-12|
    [返回顶部]