DETAILED ACTION
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claim 28 is rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claim 28 depends on claim 27, which has been cancelled.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 9, 15-16, and 28 are rejected under 35 U.S.C. 103 as being unpatentable over Tamura et al. (2015/0241629) in view of Zhou et al. (CN 107162401 machine translation provided) and Chludzinski et al. (2017/0101335). Regarding claim 9, Tamura discloses an optical fiber preform comprising an optical fiber core rod ([0039]), an alkali metal doped tube ([0038]) surrounding the optical fiber core rod ([0041]), and a cladding jacket surrounding the alkali metal doped tube ([0043], [0045]). Tamura teaches the alkali metal doped tube provides for doping of the core so as to allow a low viscosity of the core section during drawing ([0004]). Tamura teaches heating a gas of an alkali metal source and diffusing the alkali metal element through the inner surface of the glass pipe, so as to provide for the alkali metal doped tube ([0038]). Tamura further exemplifies the alkali metal source is potassium bromide (KBr), but doesn’t specify other options. Although sodium was not exemplified, it is a well-known alkali metal used in glass manufacturing. Zhou also teaches diffusion doping of a glass pipe with an alkali metal using an alkali metal source compound (4th passage on page 4). Zhou teaches the alkali metal source compound usually comprise of an alkali metal element and a halide, wherein well-known alkali metal source compounds include KBr, KCl, NaF, NaCl, NaBr, etc. (6th passage on page 4). Zhou recognizes any of these dopants can provide for a low viscosity of the core section during drawing of the optical fiber preform and allows for relaxation of the network structure of silica glass, thereby reducing the attenuation of the optical fiber (“reducing attenuation coefficient”….”alkali metal element can reduce the high temperature viscosity of the glass…adjustment of the glass network structure, reducing the Rayleigh scattering loss” in 6th passage on page 2). Accordingly, it would have been obvious to one of ordinary skill in the art at the time of the invention to have employed any of the known alkali metal source compounds suggested by Zhou, such as NaF, as an alternative for doping the glass tube of Tamura, as they will predictably provide for the desired effect of reducing attenuation of the optical fiber. In employing the well-known compound of NaF, it would have been obvious to one of ordinary skill in the art at the time of the invention to have further expect fluorine doping of the glass tube, as NaF would provide for both sodium and fluorine ions to be diffused into the glass tube.
Tamura teaches the optical fiber core is a silica glass rod ([0041]), but doesn’t suggests a core rod comprising a pure silica core surrounded by a fluorine doped cladding. Chludzinski teaches a core rod (core cane) can have several different embodiments including ones having a core of pure silica or doped silica. Chludzinski also teaches the core rod can comprise of layers, wherein one or more layers may be doped or undoped. Chludzinski teaches the combination of dopants is selected to control the refractive index of the core rod, wherein a known dopant includes fluorine ([0068], [0071]). It is well known a core of pure silica would require an adjacent layer of down doped cladding, i.e. a fluorine doped cladding, to provide the refractive index difference needed to propagate the signal down the core (claim 28). Accordingly, it would have been obvious to one of ordinary skill in the art at the time of the invention to have employed any of the known core rods, including one comprising of pure silica surrounded by a fluorine doped cladding, for the core rod of Tamura, as there a limited number of options for core rods as taught by Chludzinski, with a reasonable expectation of success.
Regarding claim 15, Tamura further teaches the cladding jacket comprises silica doped with fluorine ([0045], [0060]).
Regarding claim 16, Zhou teaches the glass tube is a silica tube ([0037], and as mentioned above, Zhou teaches the alkali metal dopant can comprise of sodium (6th passage on page 4).
Claims 17-18, 20, and 22 are rejected under 35 U.S.C. 103 as being unpatentable over Tamura et al. (2015/0241629) in view of Zhou et al. (CN 107162401 machine translation provided) and Chludzinski et al. (2017/0101335). Regarding claims 17-18, Tamura discloses an optical fiber preform comprising an optical fiber core rod ([0039]), an alkali metal doped tube ([0038]) surrounding the optical fiber core rod ([0041]), and a cladding jacket surrounding the alkali metal doped tube ([0043], [0045]). Tamura teaches the alkali metal doped tube provides for doping of the core so as to allow a low viscosity of the core section during drawing ([0004]). Tamura teaches heating a gas of the alkali metal source and diffusing the alkali metal element through the inner surface of the glass pipe, so as to provide for the alkali metal doped tube ([0038]). Tamura further exemplifies the alkali metal source is potassium bromide (KBr), but doesn’t specify other options. Although sodium was not exemplified, it is a well-known alkali metal used in glass manufacturing. Zhou also teaches diffusion doping of a glass pipe with an alkali metal using an alkali metal source compound (4th passage on page 4). Zhou teaches the alkali metal source compound usually comprise of an alkali metal element and a halide, wherein well-known alkali metal source compounds include KBr, KCl, NaF, NaCl, NaBr, etc (6th passage on page 4). Zhou recognizes any of these dopants can provide for a low viscosity of the core section during drawing of the optical fiber preform and allows for relaxation of the network structure of silica glass, thereby reducing the attenuation of the optical fiber (“reducing attenuation coefficient”….”alkali metal element can reduce the high temperature viscosity of the glass…adjustment of the glass network structure, reducing the Rayleigh scattering loss” in 6th passage on page 2). Accordingly, it would have been obvious to one of ordinary skill in the art at the time of the invention to have employed any of the known alkali metal source compounds suggested by Zhou, such as NaF, as an alternative for doping the glass tube of Tamura, as they will predictably provide for the desired effect of reducing attenuation of the optical fiber. In employing the well-known compound of NaF, it would have been obvious to one of ordinary skill in the art at the time of the invention to have further expect fluorine doping of the glass tube, as NaF would provide for both sodium and fluorine ions to be diffused into the glass tube.
Tamura teaches the optical fiber core is a silica glass rod ([0041]), but doesn’t suggests a core rod comprising a pure silica core surrounded by a fluorine doped cladding. Chludzinski teaches a core rod (core cane) can have several different embodiments including ones having a core of pure silica or doped silica. Chludzinski also teaches the core rod can comprise of layers, wherein one or more layers may be doped or undoped. Chludzinski teaches the combination of dopants is selected to control the refractive index of the core rod, wherein a known dopant includes fluorine ([0068], [0071]). It is well known a core of pure silica would require an adjacent layer of down doped cladding, i.e. a fluorine doped cladding, to provide the refractive index difference needed to propagate the signal down the core. Accordingly, it would have been obvious to one of ordinary skill in the art at the time of the invention to have employed any of the known core rods, including one comprising of pure silica surrounded by a fluorine doped cladding, for the core rod of Tamura, as there a limited number of options for core rods as taught by Chludzinski, with a reasonable expectation of success.
Regarding claim 20, Zhou teaches the glass tube is a silica tube ([0037], and as mentioned above, Zhou teaches the alkali metal dopant can comprise of sodium (6th passage on page 4).
Regarding claim 22, Tamura further teaches the cladding jacket comprises silica doped with fluorine ([0045], [0060]).
Response to Arguments
Applicant’s arguments filed March 16, 2026 have been fully considered but they are not persuasive. Applicant argues Chludzinski does not teach a pure silica core rod. Applicant points to paragraphs [0007] and [0102] and argues Chludzinski teaches an updoped core, thereby teaching away from a pure silica core. This is not found persuasive because, while Chludzinski teaches it is common to have an updoped core in the disclosure of background art ([0007]), Chludzinski specifies in [0068] that the core cane can be made from pure silica or doped silica. The disclosure of one or more alternative does not constitute a teaching away from any of the alternatives because it does not criticize or discourage the use of a pure silica core.
Conclusion
THIS ACTION IS MADE FINAL. Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
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/QUEENIE S DEHGHAN/Primary Examiner, Art Unit 1741
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