Prosecution Insights
Last updated: April 19, 2026
Application No. 18/607,705

METHOD OF MANUFACTURING OPTICAL FIBER PREFORM AND METHOD OF MANUFACTURING OPTICAL FIBER

Non-Final OA §112
Filed
Mar 18, 2024
Examiner
DEHGHAN, QUEENIE S
Art Unit
1741
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Furukawa Electric Co. Ltd.
OA Round
1 (Non-Final)
62%
Grant Probability
Moderate
1-2
OA Rounds
3y 5m
To Grant
73%
With Interview

Examiner Intelligence

Grants 62% of resolved cases
62%
Career Allow Rate
519 granted / 839 resolved
-3.1% vs TC avg
Moderate +11% lift
Without
With
+11.1%
Interview Lift
resolved cases with interview
Typical timeline
3y 5m
Avg Prosecution
52 currently pending
Career history
891
Total Applications
across all art units

Statute-Specific Performance

§101
0.3%
-39.7% vs TC avg
§103
52.9%
+12.9% vs TC avg
§102
13.2%
-26.8% vs TC avg
§112
26.1%
-13.9% vs TC avg
Black line = Tech Center average estimate • Based on career data from 839 resolved cases

Office Action

§112
DETAILED ACTION Election/Restrictions Applicant’s election without traverse of group “a”, claims 1-3 and 8-11, in the reply filed on November 26, 2025 is acknowledged. Specification The lengthy specification has not been checked to the extent necessary to determine the presence of all possible minor errors. Applicant’s cooperation is requested in correcting any errors of which applicant may become aware in the specification. 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 8 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 8 recites the limitation "the silica glass rod" in line 4. There is insufficient antecedent basis for this limitation in the claim. Claim 8 recites a second removing step of removing the silica glass rod after the removing step. Claim 8 depends on claim 1, and claim 1 fails to recite a silica glass rod. Thus, it is unclear what glass rod is being referenced or if a glass rod is required. Allowable Subject Matter Claims 1-3 and 9-11 are allowed. Claim 8 would also be allowed once the 112 issues have been resolved. The following is an examiner’s statement of reasons for allowance: Prior art that suggests the doping of a silica glass tube include Schultz et al. (3,711,262). Schultz teaches a method for manufacturing an optical fiber preform, the method comprising preparing a silica glass tube (col. 4 lines 69-75, col. 5 lines 1-5), filling the silica glass tube with a powder body containing metal component and silica powder (col.5 lines 65-75, col. 6 lines 1-13) and diffusing the alkali metal or alkaline earth metal into the silica glass tube from the powder body through a heat treatment (col. 4 lines 10-24, col. 5 lines 24-29). However, these prior art fails teach a removal step for removing the powder body that is not fixed to the silica glass tube. On the contrary, the is no intention of removing any of the powder body, as Schultz teaches sintering the powder so as become part of the optical fiber preform, thereby fixing all of the powder body to the tube (col. 6 lines 10-15, col. 7 lines 37-43). Schultz also fails to suggests doping with an alkali metal or an alkaline earth metal component. Dorn (4,867,774) also teaches a method for producing an optical fiber preform comprising similar steps, wherein a silica glass tube (col. 2 lines 30-33) is filled with a powder body comprising a dopant and silica powder (col. 1 lines 65-68, col. 2 lines 59-65). Similar to Schultz, Dorn also fails to teach a removal step or doping with an alkali metal or alkaline earth metal component. Kitamura (2018/0370841) also teaches filling a silica glass tube with a powder body comprising an alkali metal or alkaline earth metal component and silica powder ([0091], and diffusing the alkali metal or alkaline earth metal into the silica glass tube from the powder body through a heat treatment ([0023], [0030], [0093]). Kitamura also further teaches cladding an outer periphery of the silica glass tube in which the alkali metal or alkaline earth metal is diffused ([0072]-[0074]). However, Kitamura also fails to suggest removing the powder body that is not fixed to the silica glass tube. Aiso et al. (2017/0137316) teaches using a silica glass rod doped with an alkali metal for diffusing the alkali metal into a silica glass layer via a heat treatment ([0025]), and subsequently removing the silica glass rod and producing a silica glass tube diffused with alkali metal ([0026]). Aiso further teaches forming a cladding portion surrounding an outer periphery of the silica glass tube in which the alkali metal or alkaline earth metal is diffused ([0056]). While Aiso teaches removing the source of the alkali metal after diffusing, Aiso does not suggest filling a silica glass tube with a silica powder body comprising an alkali metal or alkaline earth metal and diffusing the alkali metal or alkaline earth metal into the silica glass tube. Accordingly, the prior art fails to suggest the combining the steps of diffusing an alkali metal or alkaline earth metal into a silica glass tube by filling the silica glass tube with a silica glass powder body having and alkali metal or alkaline earth metal component and heat treating to effect the diffusion of the alkali metal or alkaline earth metal, and the step of removing the powder body that is not fixed to the silica glass tube. Any comments considered necessary by applicant must be submitted no later than the payment of the issue fee and, to avoid processing delays, should preferably accompany the issue fee. Such submissions should be clearly labeled “Comments on Statement of Reasons for Allowance.” Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to QUEENIE S DEHGHAN whose telephone number is (571)272-8209. The examiner can normally be reached Monday-Friday 8:00-4:30. 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 at 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. /QUEENIE S DEHGHAN/Primary Examiner, Art Unit 1741
Read full office action

Prosecution Timeline

Mar 18, 2024
Application Filed
Jan 06, 2026
Examiner Interview (Telephonic)
Jan 09, 2026
Non-Final Rejection — §112 (current)

Precedent Cases

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

1-2
Expected OA Rounds
62%
Grant Probability
73%
With Interview (+11.1%)
3y 5m
Median Time to Grant
Low
PTA Risk
Based on 839 resolved cases by this examiner. Grant probability derived from career allow rate.

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