Prosecution Insights
Last updated: April 19, 2026
Application No. 18/417,324

ALKALI DOPED MULITCORE OPTICAL FIBER WITH REDUCED DEVITRIFICATION

Final Rejection §103
Filed
Jan 19, 2024
Examiner
DAIGLER, CHRISTOPHER PAUL
Art Unit
1741
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Corning Incorporated
OA Round
2 (Final)
56%
Grant Probability
Moderate
3-4
OA Rounds
3y 2m
To Grant
99%
With Interview

Examiner Intelligence

Grants 56% of resolved cases
56%
Career Allow Rate
5 granted / 9 resolved
-9.4% vs TC avg
Strong +57% interview lift
Without
With
+57.1%
Interview Lift
resolved cases with interview
Typical timeline
3y 2m
Avg Prosecution
39 currently pending
Career history
48
Total Applications
across all art units

Statute-Specific Performance

§101
1.3%
-38.7% vs TC avg
§103
59.1%
+19.1% vs TC avg
§102
9.3%
-30.7% vs TC avg
§112
28.3%
-11.7% vs TC avg
Black line = Tech Center average estimate • Based on career data from 9 resolved cases

Office Action

§103
Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . DETAILED ACTION Response to Applicants Arguments and Remarks The Amendment/Request for Reconsideration After Non-Final Rejection filed 12/08/2025 has been entered. Claims 1-20 remain pending in the application. Claims 1-5, 7-9, 11,13,15 and 17-20 have been amended and claims 21 and 22 have been added. Applicant’s Arguments with respect to claim(s) in the Non-Final rejection dated 12/08/2025 have been considered persuasive and have been withdrawn. Due to the Amendments filed 12/08/2025, there are new grounds of rejection necessitated by the Amendments. Claim Interpretation Examiner Note: A method is defined as a series of actions (MPEP 2106 (I), i.e., “processes…defines “actions”; inventions that consist of a series of steps or acts to be performed). Thus, since methods are defined by actions, the method is given weight only to the extent that it impacts the method in a manipulative sense. See Ex parte Pfeiffer, 135 USPQ 31, noting “recited structural limitations must affect method in manipulative sense and not amount to mere claiming of a use of a particular structure”. Regarding Claim 22, the structural limitation recited is “the first cover covers the first axial end of the core section but does not cover a first axial end of the sleeve, and the second cover covers the second axial end of the core section but does not cover a second axial end of the sleeve”. Claim Rejections - 35 USC § 103 The following is a quotation of pre-AIA 35 U.S.C. 103(a) which forms the basis for all obviousness rejections set forth in this Office action: (a) A patent may not be obtained through the invention is not identically disclosed or described as set forth in section 102, if the differences between the subject matter sought to be patented and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art to which said subject matter pertains. Patentability shall not be negated by the manner in which the invention was made. The factual inquiries for establishing a background for determining obviousness under pre-AIA 35 U.S.C. 103(a) are summarized as follows: 1. Determining the scope and contents of the prior art. 2. Ascertaining the differences between the prior art and the claims at issue. 3. Resolving the level of ordinary skill in the pertinent art. 4. Considering objective evidence present in the application indicating obviousness or nonobviousness. This application currently names joint inventors. In considering patentability of the claims under pre-AIA 35 U.S.C. 103(a), the examiner presumes that the subject matter of the various claims was commonly owned at the time any inventions covered therein were made absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and invention dates of each claim that was not commonly owned at the time a later invention was made in order for the examiner to consider the applicability of pre-AIA 35 U.S.C. 103(c) and potential pre-AIA 35 U.S.C. 102(e), (f) or (g) prior art under pre-AIA 35 U.S.C. 103(a). Claims 1-4, 17-18, 21-22 is/are rejected under 35 U.S.C. 103 as being unpatentable in view of PGPUB 20200277219A1 by Khrapko (herein “Khrapko”) and in further view of PGPUB 20050063663A1 by Anderson et. al. (herein “Anderson”). Regarding Claim 1, Khrapko teaches: A method of making a multicore optical fiber preform; [0007], “ The methods can be used to form either a single core cane-based glass preform or a multicore cane-based glass preform”. the method comprising: consolidating a preform assembly to form the multicore optical fiber preform; [0010], “ An embodiment of the disclosure is a method of forming a cane-based preform… and heating …the preform assembly…to the preform to form the cane-based glass preform.” the preform assembly comprising: a plurality of core canes such that each core cane is disposed within an axial hole of a sleeve; [0007], “ The method utilizes one or more glass cladding sections each having one or more precision axial holes formed…”, “A cane or canes are then added to the one or more axial holes to define a cane-cladding assembly.” a core section; [0111], “…each of the one or more canes comprises a glass core region surrounded by a glass inner cladding region …” each core cane comprising, the core section of each core cane being encased by the sleeve; [0016], “adding one or more canes to the respective one or more axial holes so that each axial hole includes a cane”. along a height of the core cane; Fig. 2C, element 50 (cane) inside the cladding element 10 along the height of the cane. by a first cover disposed at a first axial end of the core section and a second cover disposed at a second axial end of the core section.;[0065] , [0071], “Each cane 50 has a glass body 51 that defines a top end 52, a bottom end 54…The glass body 51 can comprise a core section 51c and an inner cladding section 51i that immediately surrounds the core section”, “FIG. 4A is a partially exploded view of an example preform assembly 150 formed using the cane-cladding assembly 120 of FIG. 2B. The preform assembly 150 includes a top cap 70 that interfaces with…the top end 13 of the glass cladding section 10. The preform assembly 150 also includes the aforementioned bottom cap 90 interfaced with the bottom end 15 of the glass cladding section 10. Both the top and bottom caps 70 and 90 comprise glass…”. Fig. 2A illustrates the cane 50, which contains the elements 51c (core region) and 51i (inner cladding). All the elements of Fig. 2A are contained in Fig. 4A , which illustrates the end caps. Khrapko teaches that a core cane 50 can have any refractive index profile that can be made using known techniques in the art as needed to achieve desired properties of the resulting optical fiber, where the cladding 51i that surrounds the cane can comprise one or more undoped of down doped inner cladding sections [0065]. As one skilled in the art would know doping changes refractive index profile, this suggests a desired a radially decreasing amount of dopant is possible. But Khrapko fails to teach, a core section comprised of a silica glass doped with an alkali dopant such that a concentration of the alkali dopant decreases radially outward from a centerline of core section the silica glass of the core section having a maximum alkali dopant concentration between about 0.10 wt % and about 10 wt%; In the same field of endeavor as manufacturing fiber preforms for optical fibers, Anderson teaches an alkali doped rod (core section) that has alkaline metal oxide concentration that decrease radially outward form the centerline of the core section ([0095], Fig. 17) where Fig. 17 shows the alkali metal oxide as K2O with the maximum alkali dopant concentration of 1.0 wt%. in glass rod 132. Further, rod 132 can be processed and drawn into a smaller glass rod 144 where the K2O wt. % content is 2%-4% wt. Then, alkali doped glass rod 144 is inserted into optical fiber preform 150 ([0096]). It would have been obvious to one of ordinary skill in the art at the time of the effective filing date of the claimed invention to use the alkali doped glass rod with a radially decreasing alkali concentration of Anderson in the method of Khrapko, as one would have been motivated to do so for the purpose of creating a stepped index fiber, which is common in the art, as well as offsetting the migration of the alkali dopant in the alkali doped glass rod during the draw of the optical fiber to meet the wt% K2O desired in the optical fiber, as noted by Anderson ([0096], lines 23-31). While Khrapko teaches first and second covers, Khrapko fails to teach, the first cover and the second cover each comprising silica glass having a chlorine concentration of about 0.05 wt.% or less. Anderson further teaches an alkali doped rod with radially decreasing alkali content rod 132 is made from tube 106, where dopants, including the alkali dopants, are added to tube 106, and cites that all glass added to be essentially chlorine free with a chlorine content less than 500ppm (.05%wt) to avoid optical losses due to alkali chloride crystallization ([0090]). It would have been obvious to one of ordinary skill in the art prior at the time of the effective filing date of the claimed invention to use the wt % Cl of the alkali doped glass rod in Anderson for the wt% Cl of the covers in Khrapko, not only for the reason above, for also as it is known in the art that low levels of Cl reduce fiber attenuation. A person of ordinary skill has good reason to pursue the known option within his or her technical grasp. If this leads to the anticipated success, it is likely the product not of innovation but of ordinary skill and common sense." KSR int'l Co. v. Teleflex Inc., 127 S.Ct. 1727,82 USPQ2d 1385 (2007). Regarding Claim 2 and 3 - Khrapko and Anderson in the rejection of claim 1 above teach all of the limitations of claim 1. wherein, the alkali dopant is sodium, potassium, rubidium, cesium, or a combination thereof (Claim 2) wherein, the alkali dopant is potassium (Claim 3) Anderson teaches the instant Claims 2 and Claim 3 previously in Claim 1. Regarding Claim 4 - Khrapko and Anderson in the rejection of claim 1 above teach all of the limitations of claim 1. wherein the maximum alkali dopant concentration in the core section is between about 0.4 wt.% and about 5.0 wt.%. Anderson teaches and alkali doped glass rod 132 where the alkali metal oxide as K2O with the maximum alkali dopant concentration of 1.0 wt%. in glass rod 132. Further, rod 132 can be processed and drawn into a smaller glass rod 144 where the K2O wt. % content is 2%-4% wt. to offset the migration of the alkali dopant in the alkali doped glass rod during the draw of the optical fiber to meet the wt% K2O desired in the optical fiber([0096]). Overlapping ranges are prima facie evidence of obviousness. It would have been obvious to one having ordinary skill in the art prior to the effective filing date of the claimed invention to have selected the portion of Anderson’s alkali dopant concentration range of that corresponds to the claimed range. See MPEP 2144.05. Regarding Claim 17 - Khrapko and Anderson in the rejection of claim 1 above teach all of the limitations of claim 1. Khrapko further teaches wherein, a diameter of the first axial end is perpendicular to a height of the core section, and a diameter of the second axial end is perpendicular to the height of the core section; Fig. 2A, elements 50, 52, 54, 51c and 51i, [0065] lines 1-3, “ FIG. 2A includes a close-up inset showing an example cane 50. Each cane 50 has a glass body 51 that defines a top end 52, a bottom end 54…” Regarding Claim 18 - Khrapko and Anderson in the rejection of claim 1 above teach all of the limitations of claim 1. Khrapko further teaches wherein, each core cane comprises an inner cladding section disposed radially outward of the core section; Fig. 2A, elements 50/51c/51i, [0111], “each of the one or more canes comprises a glass core region surrounded by a glass inner cladding region.” Regarding Claim 21, Khrapko and Anderson in the rejection of claim 1 above teach all of the limitations of claim 1. wherein radially outer portions of the core section do not comprise the alkali dopant. Anderson further teaches an alkali doped glass rod with a radially decreasing concentration of potassium is preferably formed without any significant alkali metal oxide dopant present at the outer radius and that having a layer on the rod without alkali dopant reduces the propensity for crystallization at the rod interface if chlorine is present in later processing ([0095], lines 12-20) Fig 17, element 171. It would have been obvious to one having ordinary skill in the art at the time of the effective filing date of the claimed invention was made to use the structure of the alkali doped glass rod of Anderson in core cane of Khrapko, one being motivated to do so for the reason noted above (reduces the propensity for crystallization ) at the rod interface if chlorine is present in later processing by Anderson Regarding Claim 22, Khrapko and Anderson in the rejection of claim 1 above teach all of the limitations of claim 1. Claim 22 is considered to be directed to a structural limitation only. While it does not directly impact the claimed method steps, Khrapko further teaches wherein, the first cover covers the first axial end of the core section but does not cover a first axial end of the sleeve, and the second cover covers the second axial end of the core section but does not cover a second axial end of the sleeve. Khrapko discloses the claimed invention except for the locations of the engagement and structure of the covers on the sleeve. It would have been obvious to one of ordinary skill in the art at the time of the effective filing date of the claimed invention to determine the engagement and structure of the sleeves, since it has been held that a mere change in shape of an element is generally recognized as being within the level of ordinary skill in art when the change in shape is not significant to the function of the combination. Further, one would have been motivated to select the shape of covers for the purpose of achieving the intended sealing function. It has been held that a mere change in shape without affecting the functioning of the part would have been within the level of ordinary skill in the art, In re Dailey et al., 149 USPQ 47; Eskimo Pie Corp. v, Levous et aI., 3 USPQ 23. Claims 5-16 is/are rejected under 35 U.S.C. 103 as being unpatentable in view of PGPUB 20200277219A1 by Khrapko (herein “Khrapko”) and in further view of PGPUB 20050144986A1 by Anderson et. al. (herein “Anderson”) and in further view of U.S. Patent 9,878,940 by Baker et. al. (herein “Baker”) and in further view of PGPUB 20200017399A1 by Click et. al (herein “Click”). Regarding Claim 5 - Khrapko and Anderson in the rejection of claim 1 above teach all of the limitations of claim 1. where the maximum alkali dopant concentration is between about 0.50 wt.% and about 10 wt.%; Anderson teaches and alkali doped glass rod 132 where the alkali metal oxide as K2O with the maximum alkali dopant concentration of 1.0 wt%. in glass rod 132. Further, rod 132 can be processed and drawn into a smaller glass rod 144 where the K2O wt. % content is 2%-4% wt. to offset the migration of the alkali dopant in the alkali doped glass rod during the draw of the optical fiber to meet the wt% K2O desired in the optical fiber([0096]). Overlapping ranges are prima facie evidence of obviousness. It would have been obvious to one having ordinary skill in the art prior to the effective filing date of the claimed invention to have selected the portion of Anderson’s alkali dopant concentration range of that corresponds to the claimed range. See MPEP 2144.05. and consolidating the preform assembly comprises exposing the preform assembly to a temperature T (K) for a time t (sec) such that: t < tc, and tc=10(1.86x10-10T4-9.69x10-7T3+1.91x10-3T2-1.68T+571.9), wherein tc is a time (sec) for the glass to crystalize. In the similar field of endeavor as controlling crystallization in glass compositions useable for core cane of a fiber preform, Baker teaches a glass composition (Col 2 lines 61-67, Col 3 lines 1-3) in mol% converted to wt% below: PNG media_image1.png 200 400 media_image1.png Greyscale Further, Baker cites heat treating crystallizable glasses at one or more preselected temperatures and one or more preselected times to induce crystallization, suggesting a crystallization temperature of about 575°C to 900°C and holding temperature in this range for ¼-4 hrs. to produce a glass ceramic ([Col 17 lines 36-57). Baker teaches the claim except for use specifically on a core cane rod, and a specific time not to induce crystallization. It would have been obvious to one having ordinary skill in the art at the time of the effective filing date of the claimed invention was made to use the temperature and time methods of the crystallizable glass of Baker that induces crystallization to support not inducing crystallization in the similar glass of the core rod during consolidation of the combination, as material crystallization applies to any process that involved heat treatment. One would have been motivated to do so as Baker notes crystallized glass produces crystalline phases, major and minor crystalline phases, influence on integrity, and opacity (col 18 lines 1-9); all items that are undesired in a fiber optic preform to be used to fabricate optical fiber. But Baker fails to teach t < tc, and tc=101.86x10-10T4-9.69x10-7T3+1.91x10-3T2-1.68T+571.9, wherein tc is the time (sec) for the glass to crystalize, i.e. a time temperature relationship regarding crystallization. In the similar field of endeavor as controlling crystallization in glass compositions useable for core cane of a fiber preform, Click teaches a similar composition of crystallizable glass similar to the core cane glass, which can include Na2O, K2O, Rb2O or Cs2O ([0044]). Further, Click cites an equation containing crystallization temperature and crystallization time ([0009]) as follows: “In a fifth aspect, a method of forming a glass-ceramic article, the method comprises: heating a glass composition to a nucleation temperature (TN); maintaining the nucleation temperature for a first predetermined period of time (tN) to produce a nucleated crystallizable glass composition; heating the nucleated crystallizable glass composition to a crystallization temperature (TC); and maintaining the crystallization temperature for a second predetermined period of time (tC) to produce the glass-ceramic article, wherein: (103−0.260TN+0.000203(TN)2−7.96tN+0.1532(tN)2−0.019TC−0.000008(TC)2−10.03tC+0.00597TN*tN+0.00463 tN*TC+0.01342TC*tC)<0.2. While Click teaches a relationship between time, temperature and crystallization, Click does not teach the exact relationship of the claim. I t would have been obvious to one having ordinary skill in the art at the time of the effective filing date of the claimed invention to have used a different equation for the time/temperature/crystallization relationship since it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art. One would have been motivated to determine an optimum equation for the purpose of supporting the specific glass composition in use. Where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation. It would have been obvious to one having ordinary skill in the art to have determined the optimum values of the relevant process parameters through routine experimentation in the absence of a showing of criticality. In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235. Regarding Claim 6, which depends on Claim 5 – Khrapko, Anderson, Baker and Click in the rejection of claim 5 above teach all of the limitations of claim 5. Wherein, the temperature T is between about 1000 K and about 1925 K; Note: 1000K=727°C, 1925K=1652°C. Baker further teaches suggesting a crystallization temperature of about 575°C to 900°C ([Col 17 lines 51-53). Overlapping ranges are prima facie evidence of obviousness. It would have been obvious to one having ordinary skill in the art prior to the effective filing date of the claimed invention to have selected the portion of Baker’s temperature range that corresponds to the claimed range. See MPEP 2144.05. Regarding Claim 7 and 8, which both depend ultimately on Claim 6 - Khrapko, Anderson, Baker and Click in the rejection of claim 5 above teach all of the limitations of claim 5. Wherein, the maximum alkali dopant concentration is between about 0.75 wt.% and about 4 wt.%. the maximum alkali dopant concentration is between about 0.78 wt.% wt.% and about 4 wt.%. Anderson teaches and alkali doped glass rod 132 where the alkali metal oxide as K2O with the maximum alkali dopant concentration of 1.0 wt%. in glass rod 132. Further, rod 132 can be processed and drawn into a smaller glass rod 144 where the K2O wt. % content is 2%-4% wt. to offset the migration of the alkali dopant in the alkali doped glass rod during the draw of the optical fiber to meet the wt% K2O desired in the optical fiber([0096]). Overlapping ranges are prima facie evidence of obviousness. It would have been obvious to one having ordinary skill in the art prior to the effective filing date of the claimed invention to have selected the portion of Anderson’s alkali dopant concentration range of that corresponds to the claimed range. See MPEP 2144.05. Regarding Claim 9 - Khrapko and Anderson in the rejection of claim 1 above teach all of the limitations of claim 1. wherein the maximum alkali dopant concentration is between about 0.50 wt.% and about 10 wt.% Anderson teaches and alkali doped glass rod 132 where the alkali metal oxide as K2O with the maximum alkali dopant concentration of 1.0 wt%. in glass rod 132. Further, rod 132 can be processed and drawn into a smaller glass rod 144 where the K2O wt. % content is 2%-4% wt. to offset the migration of the alkali dopant in the alkali doped glass rod during the draw of the optical fiber to meet the wt% K2O desired in the optical fiber([0096]). Overlapping ranges are prima facie evidence of obviousness. It would have been obvious to one having ordinary skill in the art prior to the effective filing date of the claimed invention to have selected the portion of Anderson’s alkali dopant concentration range of that corresponds to the claimed range. See MPEP 2144.05. The combination fails to teach: and consolidating the preform assembly comprises exposing the preform assembly to a temperature T (K) for a time t (sec) such that: t < tc, and tc=10(1.86x10-10T4-9.69x10-7T3+1.91x10-3T2-1.68T+571.9),, wherein tc is a time (sec) for the glass to crystallize. In the similar field of endeavor as controlling crystallization in glass compositions useable for core cane of a fiber preform, Baker teaches a glass composition within claimed ranges of the instant application (Col 2 lines 61-67, Col 3 lines 1-3) in mol% converted to wt% below: PNG media_image1.png 200 400 media_image1.png Greyscale Further, Baker cites heat treating crystallizable glasses at one or more preselected temperatures and one or more preselected times to induce crystallization, suggesting a crystallization temperature of about 575°C to 900°C and holding temperature in this range for ¼-4 hrs. to produce a glass ceramic ([Col 17 lines 36-57). Baker teaches the claim except for use specifically on a core cane rod, and a specific time not to induce crystallization. It would have been obvious to one having ordinary skill in the art at the time of the effective filing date of the claimed invention was made to use the temperature and time methods of the crystallizable glass of Baker that induces crystallization to support not inducing crystallization in the similar glass of the core rod during consolidation of the combination, as material crystallization applies to any process that involved heat treatment. One would have been motivated to do so as Baker notes crystallized glass produces crystalline phases, major and minor crystalline phases, influence on integrity, and opacity (col 18 lines 1-9); all items that are undesired in a fiber optic preform to be used to fabricate optical fiber. But Baker fails to teach t < tc, and tc=101.86x10-10T4-9.69x10-7T3+1.91x10-3T2-1.68T+571.9, wherein tc is the time (sec) for the glass to crystalize, i.e. a time temperature relationship regarding crystallization. In the similar field of endeavor as controlling crystallization in glass compositions useable for core cane of a fiber preform, Click teaches a similar composition of crystallizable glass similar to the core cane glass, which can include Na2O, K2O, Rb2O or Cs2O ([0044]). Further, Click cites an equation containing crystallization temperature and crystallization time ([0009]) as follows: “In a fifth aspect, a method of forming a glass-ceramic article, the method comprises: heating a glass composition to a nucleation temperature (TN); maintaining the nucleation temperature for a first predetermined period of time (tN) to produce a nucleated crystallizable glass composition; heating the nucleated crystallizable glass composition to a crystallization temperature (TC); and maintaining the crystallization temperature for a second predetermined period of time (tC) to produce the glass-ceramic article, wherein: (103−0.260TN+0.000203(TN)2−7.96tN+0.1532(tN)2−0.019TC−0.000008(TC)2−10.03tC+0.00597TN*tN+0.00463 tN*TC+0.01342TC*tC)<0.2. While Click teaches a relationship between time, temperature and crystallization, Click does not teach the exact relationship of the claim. I t would have been obvious to one having ordinary skill in the art at the time of the effective filing date of the claimed invention to have used a different equation for the time/temperature/crystallization relationship since it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art. One would have been motivated to determine an optimum equation for the purpose of supporting the specific glass composition in use. Where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation. It would have been obvious to one having ordinary skill in the art to have determined the optimum values of the relevant process parameters through routine experimentation in the absence of a showing of criticality. In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 Regarding Claim 10, which depends on claim 9 - Khrapko, Anderson, Baker and Click in the rejection of claim 9 above teach all of the limitations of claim 9. Wherein, the temperature T is between about 1000 K and about 1925 K; Note: 1000K=727°C, 1925K=1652°C. Baker further teaches suggesting a crystallization temperature of about 575°C to 900°C ([Col 17 lines 51-53). Overlapping ranges are prima facie evidence of obviousness. It would have been obvious to one having ordinary skill in the art prior to the effective filing date of the claimed invention to have selected the portion of Baker’s temperature range that corresponds to the claimed range. See MPEP 2144.05. Regarding Claim 11 and 12 - Khrapko, Anderson, Baker and Click in the rejection of claim 9 above teach all of the limitations of claim 9. Wherein, the maximum alkali dopant concentration is between about 0.75 wt.% and about 4 wt.%. the maximum alkali dopant concentration is between about 0.78 wt.% wt.% and about 4 wt.%. Anderson teaches and alkali doped glass rod 132 where the alkali metal oxide as K2O with the maximum alkali dopant concentration of 1.0 wt%. in glass rod 132. Further, rod 132 can be processed and drawn into a smaller glass rod 144 where the K2O wt. % content is 2%-4% wt. to offset the migration of the alkali dopant in the alkali doped glass rod during the draw of the optical fiber to meet the wt% K2O desired in the optical fiber([0096]). Overlapping ranges are prima facie evidence of obviousness. It would have been obvious to one having ordinary skill in the art prior to the effective filing date of the claimed invention to have selected the portion of Anderson’s alkali dopant concentration range of that corresponds to the claimed range. See MPEP 2144.05. Regarding Claim 13 - Khrapko and Anderson in the rejection of claim 1 above teach all of the limitations of claim 1. Wherein, the maximum alkali dopant concentration is between about 1.56 wt.% and about 4 wt.%, Anderson teaches and alkali doped glass rod 132 where the alkali metal oxide as K2O with the maximum alkali dopant concentration of 1.0 wt%. in glass rod 132. Further, rod 132 can be processed and drawn into a smaller glass rod 144 where the K2O wt. % content is 2%-4% wt. to offset the migration of the alkali dopant in the alkali doped glass rod during the draw of the optical fiber to meet the wt% K2O desired in the optical fiber([0096]). Overlapping ranges are prima facie evidence of obviousness. It would have been obvious to one having ordinary skill in the art prior to the effective filing date of the claimed invention to have selected the portion of Anderson’s alkali dopant concentration range of that corresponds to the claimed range. See MPEP 2144.05. and consolidating the preform assembly comprises exposing the preform assembly to a temperature T (K) for a time t (sec) such that: t < tc, and tc=10(1.67x10-10T4-8.68x10-7T3+1.7x10-3T2-1.5T+506), wherein tc a the time (sec) for the glass to crystallize. In the similar field of endeavor as controlling crystallization in glass compositions useable for core cane of a fiber preform, Baker teaches a glass composition within claimed ranges of the instant application (Col 2 lines 61-67, Col 3 lines 1-3) in mol% converted to wt% below: PNG media_image1.png 200 400 media_image1.png Greyscale Further, Baker cites heat treating crystallizable glasses at one or more preselected temperatures and one or more preselected times to induce crystallization, suggesting a crystallization temperature of about 575°C to 900°C and holding temperature in this range for ¼-4 hrs. to produce a glass ceramic ([Col 17 lines 36-57). Baker teaches the claim except for use specifically on a core cane rod, and a specific time not to induce crystallization. It would have been obvious to one having ordinary skill in the art at the time of the effective filing date of the claimed invention was made to use the temperature and time methods of the crystallizable glass of Baker that induces crystallization to support not inducing crystallization in the similar glass of the core rod during consolidation of the combination, as material crystallization applies to any process that involved heat treatment. One would have been motivated to do so as Baker notes crystallized glass produces crystalline phases, major and minor crystalline phases, influence on integrity, and opacity (col 18 lines 1-9); all items that are undesired in a fiber optic preform to be used to fabricate optical fiber. But Baker fails to teach t < tc, and tc=101.86x10-10T4-9.69x10-7T3+1.91x10-3T2-1.68T+571.9, wherein tc is the time (sec) for the glass to crystalize, i.e. a time temperature relationship regarding crystallization. In the similar field of endeavor as controlling crystallization in glass compositions useable for core cane of a fiber preform, Click teaches a similar composition of crystallizable glass similar to the core cane glass, which can include Na2O, K2O, Rb2O or Cs2O ([0044]). Further, Click cites an equation containing crystallization temperature and crystallization time ([0009]) as follows: “In a fifth aspect, a method of forming a glass-ceramic article, the method comprises: heating a glass composition to a nucleation temperature (TN); maintaining the nucleation temperature for a first predetermined period of time (tN) to produce a nucleated crystallizable glass composition; heating the nucleated crystallizable glass composition to a crystallization temperature (TC); and maintaining the crystallization temperature for a second predetermined period of time (tC) to produce the glass-ceramic article, wherein: (103−0.260TN+0.000203(TN)2−7.96tN+0.1532(tN)2−0.019TC−0.000008(TC)2−10.03tC+0.00597TN*tN+0.00463 tN*TC+0.01342TC*tC)<0.2. While Click teaches a relationship between time, temperature and crystallization, Click does not teach the exact relationship of the claim. I t would have been obvious to one having ordinary skill in the art at the time of the effective filing date of the claimed invention to have used a different equation for the time/temperature/crystallization relationship since it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art. One would have been motivated to determine an optimum equation for the purpose of supporting the specific glass composition in use. Where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation. It would have been obvious to one having ordinary skill in the art to have determined the optimum values of the relevant process parameters through routine experimentation in the absence of a showing of criticality. In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 Regarding Claim 14, which depends on claim 13 - Khrapko, Anderson, Baker and Click in the rejection of claim 13 above teach all of the limitations of claim 13. Wherein, the temperature T is between about 1000 K and about 1925 K; Note: 1000K=727°C, 1925K=1652°C. Baker further teaches suggesting a crystallization temperature of about 575°C to 900°C ([Col 17 lines 51-53). Overlapping ranges are prima facie evidence of obviousness. It would have been obvious to one having ordinary skill in the art prior to the effective filing date of the claimed invention to have selected the portion of Baker’s temperature range that corresponds to the claimed range. In re Malagari, 184 USPQ 549 (CCPA 1974). Regarding Claim 15 - Khrapko and Anderson in the rejection of claim 1 above teach all of the limitations of claim 1. Wherein, the maximum alkali concentration is between about 1.56 wt.% and about 4 wt.%, Anderson teaches and alkali doped glass rod 132 where the alkali metal oxide as K2O with the maximum alkali dopant concentration of 1.0 wt%. in glass rod 132. Further, rod 132 can be processed and drawn into a smaller glass rod 144 where the K2O wt. % content is 2%-4% wt. to offset the migration of the alkali dopant in the alkali doped glass rod during the draw of the optical fiber to meet the wt% K2O desired in the optical fiber([0096]). Overlapping ranges are prima facie evidence of obviousness. It would have been obvious to one having ordinary skill in the art prior to the effective filing date of the claimed invention to have selected the portion of Anderson’s alkali dopant concentration range of that corresponds to the claimed range. See MPEP 2144.05. and consolidating the preform assembly comprises exposing the preform assembly to a temperature T (K) for a time t (sec) such that: t < tc, and tc=10(1.67x10-10T4-8.68x10-7T3+1.7x10-3T2-1.5T+506), wherein tc is a time (sec) for the glass to crystallize. In the similar field of endeavor as controlling crystallization in glass compositions useable for core cane of a fiber preform, Baker teaches a glass composition within claimed ranges of the instant application (Col 2 lines 61-67, Col 3 lines 1-3) in mol% converted to wt% below: PNG media_image1.png 200 400 media_image1.png Greyscale Further, Baker cites heat treating crystallizable glasses at one or more preselected temperatures and one or more preselected times to induce crystallization, suggesting a crystallization temperature of about 575°C to 900°C and holding temperature in this range for ¼-4 hrs. to produce a glass ceramic ([Col 17 lines 36-57). Baker teaches the claim except for use specifically on a core cane rod, and a specific time not to induce crystallization. It would have been obvious to one having ordinary skill in the art at the time of the effective filing date of the claimed invention was made to use the temperature and time methods of the crystallizable glass of Baker that induces crystallization to support not inducing crystallization in the similar glass of the core rod during consolidation of the combination, as material crystallization applies to any process that involved heat treatment. One would have been motivated to do so as Baker notes crystallized glass produces crystalline phases, major and minor crystalline phases, influence on integrity, and opacity (col 18 lines 1-9); all items that are undesired in a fiber optic preform to be used to fabricate optical fiber. But Baker fails to teach t < tc, and tc=101.86x10-10T4-9.69x10-7T3+1.91x10-3T2-1.68T+571.9, wherein tc is the time (sec) for the glass to crystalize, i.e. a time temperature relationship regarding crystallization. In the similar field of endeavor as controlling crystallization in glass compositions useable for core cane of a fiber preform, Click teaches a similar composition of crystallizable glass similar to the core cane glass, which can include Na2O, K2O, Rb2O or Cs2O ([0044]). Further, Click cites an equation containing crystallization temperature and crystallization time ([0009]) as follows: “In a fifth aspect, a method of forming a glass-ceramic article, the method comprises: heating a glass composition to a nucleation temperature (TN); maintaining the nucleation temperature for a first predetermined period of time (tN) to produce a nucleated crystallizable glass composition; heating the nucleated crystallizable glass composition to a crystallization temperature (TC); and maintaining the crystallization temperature for a second predetermined period of time (tC) to produce the glass-ceramic article, wherein: (103−0.260TN+0.000203(TN)2−7.96tN+0.1532(tN)2−0.019TC−0.000008(TC)2−10.03tC+0.00597TN*tN+0.00463 tN*TC+0.01342TC*tC)<0.2. While Click teaches a relationship between time, temperature and crystallization, Click does not teach the exact relationship of the claim. It would have been obvious to one having ordinary skill in the art at the time of the effective filing date of the claimed invention to have used a different equation for the time/temperature/crystallization relationship since it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art. One would have been motivated to determine an optimum equation for the purpose of supporting the specific glass composition in use. Where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation. It would have been obvious to one having ordinary skill in the art to have determined the optimum values of the relevant process parameters through routine experimentation in the absence of a showing of criticality. In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235. Regarding Claim 16, which depends on claim 15 - Khrapko, Anderson, Baker and Click in the rejection of claim 15 above teach all of the limitations of claim 15. Wherein, the temperature T is between about 1000 K and about 1925 K; Note: 1000K=727°C, 1925K=1652°C. Baker further teaches suggesting a crystallization temperature of about 575°C to 900°C ([Col 17 lines 51-53). Overlapping ranges are prima facie evidence of obviousness. It would have been obvious to one having ordinary skill in the art prior to the effective filing date of the claimed invention to have selected the portion of Baker’s temperature range that corresponds to the claimed range. In re Malagari, 184 USPQ 549 (CCPA 1974). Claims 19 and 20 is/are rejected under 35 U.S.C. 103 as being unpatentable in view of PGPUB 202002772219A1 by Khrapko (herein “Khrapko”) and in further view of and in further view of PGPUB 20050144986A1 by Anderson et. al. (herein “Anderson”) and in further view of WO2020105470A1 (English language translation of the Description and provided herewith and referenced herein) by Matsui et. al. (herein “Matsui”). Regarding Claim 19, which depends on Claim 18 - Khrapko and Anderson in the rejection of claim 1 above teach all of the limitations of claim 1. wherein, a relative refractive index of the core section is greater than a relative refractive index of the inner cladding section. Khrapko teaches the inner cladding can have any index profile and that the cane 50 can have any index profile but fails to teach the alkali doped core region relative refractive index is greater than a relative refractive index of the inner cladding section. In the similar field of endeavor of manufacturing optical fiber, Matsui teaches a multicore optical fiber manufactured from an optical fiber preform (Page 1 lines 26-32), as one skilled in the art would know the property of index of refraction of segments of a preform transfer to the fiber when a preform is drawn. Further, Matsui teaches the inner core region with a region relative refractive index is greater than a relative refractive index of the inner cladding section; Fig. 1, Page 4 lines 30-32, “The optical fiber 15 is a multi-core optical fiber and has four cores 10 of radius a1 arranged in a square lattice along the longitudinal direction and a relative refractive index difference of Δ1 between the cores 10 and the refractive index around the core 10.” The term Δ1 being positive signifies the relative index of the core is greater than the relative index around the core, around the core meaning the first cladding 11. It would have been obvious to one having ordinary skill in the art at the time of the effective filing date of the claimed invention was made to have the core with a greater relative refractive index than the first cladding of Matsui included in the preform of Khrapko to confine the electric field distribution to the core region to reduce cross-talk of the drawn fibers, as note by Matsui (Page 2 lines 14-15). Regarding Claim 20 - Khrapko and Anderson in the rejection of claim 1 above teach all of the limitations of claim 1. Wherein, a relative refractive index of the core is greater than a relative refractive index of the sleeve. Khrapko teaches the inner cladding can have any index profile and that the cane 50 can have any index profile but fails to teach the alkali doped core region relative refractive index is greater than a relative refractive index of the sleeve. In the similar field of endeavor of manufacturing optical fiber, Matsui teaches a multicore optical fiber manufactured from an optical fiber preform (Page 1 lines 26-32), as one skilled in the art would know the property of index of refraction of segments of a preform transfer to the fiber when a preform is drawn. Further, Matsui teaches the inner core region with a region relative refractive index is greater than a relative refractive index of the sleeve; Fig. 1 Page 4 Lines 32-34, “The first cladding region 11 has a radius a2 lower than that of the core, and the outer periphery of the first cladding region 11 has a larger refractive index than the first cladding region and the relative refractive index difference from the core is Δ2. And a second cladding region 12 having a refractive index lower than that of the core.” The term Δ2 being positive signifies the relative index of the core is greater than the relative index around the second cladding (sleeve), around the core meaning It would have been obvious to one having ordinary skill in the art at the time of the effective filing date of the claimed invention was made to have the core with a greater relative refractive index than the sleeve of Matsui included in the preform of Khrapko to reduce bending radius losses as note by Matsui (Page 2 lines 9-12). Conclusion Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). 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. Any inquiry concerning this communication or earlier communications from the examiner should be directed to CHRISTOPHER PAUL DAIGLER whose telephone number is (571)272-1066. The examiner can normally be reached Monday-Friday 7:30-4:30 CT. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Alison Hindenlang can be reached on 571-270-7001. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /CHRISTOPHER PAUL DAIGLER/ Examiner, Art Unit 1741 /ALISON L HINDENLANG/Supervisory Patent Examiner, Art Unit 1741
Read full office action

Prosecution Timeline

Jan 19, 2024
Application Filed
Sep 05, 2025
Non-Final Rejection — §103
Dec 08, 2025
Response Filed
Feb 10, 2026
Final Rejection — §103
Apr 01, 2026
Request for Continued Examination
Apr 05, 2026
Response after Non-Final Action

AI Strategy Recommendation

Get an AI-powered prosecution strategy using examiner precedents, rejection analysis, and claim mapping.
Powered by AI — typically takes 5-10 seconds

Prosecution Projections

3-4
Expected OA Rounds
56%
Grant Probability
99%
With Interview (+57.1%)
3y 2m
Median Time to Grant
Moderate
PTA Risk
Based on 9 resolved cases by this examiner. Grant probability derived from career allow rate.

Sign in with your work email

Enter your email to receive a magic link. No password needed.

Personal email addresses (Gmail, Yahoo, etc.) are not accepted.

Free tier: 3 strategy analyses per month