Prosecution Insights
Last updated: April 19, 2026
Application No. 18/254,108

VERY LARGE MODE AREA SINGLE-MODE AMPLIFYING OPTICAL FIBER AND FIBER AMPLIFIER OR LASER INCORPORATING THE SAME

Non-Final OA §103§112
Filed
May 23, 2023
Examiner
MANNO, JESSICA S
Art Unit
2898
Tech Center
2800 — Semiconductors & Electrical Systems
Assignee
Photonics Bretagne
OA Round
1 (Non-Final)
72%
Grant Probability
Favorable
1-2
OA Rounds
2y 10m
To Grant
96%
With Interview

Examiner Intelligence

Grants 72% — above average
72%
Career Allow Rate
142 granted / 197 resolved
+4.1% vs TC avg
Strong +24% interview lift
Without
With
+24.3%
Interview Lift
resolved cases with interview
Typical timeline
2y 10m
Avg Prosecution
7 currently pending
Career history
204
Total Applications
across all art units

Statute-Specific Performance

§103
43.1%
+3.1% vs TC avg
§102
36.5%
-3.5% vs TC avg
§112
13.7%
-26.3% vs TC avg
Black line = Tech Center average estimate • Based on career data from 197 resolved cases

Office Action

§103 §112
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 . Claim Interpretation Claims 1-13 and 15 include the limitations of a “very large mode area” amplifying optical fiber which is generally a relative term. However, the specification provides the following special technical definition of this term. See specification, page 2, lines 12-15: “More recently, very large mode area fibers are currently under development worldwide. A very large mode area fiber (or VLMA fiber) is defined as an optical fiber having an effective area for the fundamental mode higher than approximately 375 ƛ2 where ƛ is the wavelength of the signal.” This is the meaning of the term “very large mode area” for purposes of examination. 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. Claims 1-16 are 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. Regarding claim 1, the term “transverse” lacks clarity because it is unclear how flat surfaces extend across an axis. It is suggested to change “traverse” to “perpendicular” as supported by the specification (page 9, lines 29-30) and drawing (Figure 1), this is the interpretation for purposes of examination. Regarding claim 1, the term “is suitable for being bent” lacks clarity because it is unclear how if this limitation requires that the fiber is bent or is capable of bending. For purposes of examination, it is assumed that this means that it is “capable of bending”. Claims 2-16 are rejected as they inherit the indefiniteness of the claims from which they depend. 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. Claim(s) 1, 3, 6, 8, 12-14, and 16 are rejected under 35 U.S.C. 103 as being unpatentable over Khitrov US 2009/0262761, herein after Khitrov ‘761. Regarding claim 1, Khitrov ‘761 discloses a very large mode area single-mode amplifying optical fiber (a panda-type PM-LMA, Yb-doped optical fiber-paragraphs 21-23, Figures 1-2) comprising: a core (37) extending along a longitudinal axis (axis of the fiber-Figure 2) of the optical fiber (24), the core being solid and doped with elements presenting at least one emission band (Yb-doped), the core (37) having a core diameter 30 micrometers (Paragraph 23), said core (37) being surrounded by at least one glassy cladding (Figure 2, paragraph 23) comprising a first cladding (Figure 2, 250 micron octagonally-shaped inner cladding),the first cladding comprising a solid matrix made of a first glass (silicate) and two stress applying parts (35-boro silicate stress rods-Figure 2) arranged symmetrically with respect to the core (Figure 2), the first glass having a lower refractive index than the core (37), the core (37) and the two stress applying parts (35) being aligned along an alignment axis (figure 2-rods 35 are aligned on an axis crossing through the centers of the rods and core 37) transverse to the longitudinal axis (fiber axis), wherein the at least one glassy cladding (Figure 2) comprises on its outer periphery, two flat surfaces (shown in Figure 2) extending parallel to the longitudinal axis (as defined above) and perpendicular to the alignment axis (fiber axis), the two flat surfaces being arranged symmetrically with respect to the core (37) and being joined by two rounded surfaces (Figure 2) and that the optical fiber (24) is suitable for being bent with a bending diameter below 30 cm in a plane (Paragraph 21 discloses coiling onto a 8cm mandrel) comprising the longitudinal axis of the fiber and said plane forming an angle of less than 15 degrees with the alignment axis (Figure 2) while having bending losses for the fundamental mode less than 0.5 dB/m (Paragraph 24, losses less than 0.01dB/m). Khitrov ‘761 does not specifically disclose that the core diameter is larger than 30 micrometers. However, it would have been obvious to modify the diameter to larger than 30 micrometers as claimed as there does not appear to be a technical different between with a larger diameter and the it would have been obvious to try a larger diameter. Regarding claim 3, Khitrov ‘761 further discloses that the optical fiber (24) is bent in a plane forming an angle of less than 10 degrees with the alignment axis (Paragraph 21 discloses coiling onto an 8cm mandrel, wherein a coil configuration would meet this limitation). Regarding claim 6, Khitrov ‘761 further discloses that the core (37) is doped with rare earth ions or with chromium ions (Paragraph 23-Yb-doped). Regarding claim 8, Khitrov ‘761 further discloses that the at least one glassy cladding (Figure 2) consists of the first cladding (37), the first cladding comprising, on its outer periphery, the two flat surfaces (see Figure 2). Regarding claim 12, Khitrov ‘761 further discloses that the very large mode area single-mode amplifying optical fiber (Figures 1-2) being spooled with a bending diameter less than 30 cm (Paragraph 21 discloses coiling onto an 8cm mandrel). Regarding claim 13, Khitrov ‘761 further discloses that the very large mode area single-mode amplifying optical fiber (100) has a length comprised between 50 cm and 20 m (Paragraph 21). Regarding claims 14 and 16, Khitrov ‘761 further discloses a fiber amplifier (Figure 1) comprising a pump source (26) generating a pumping beam and an optical beam combiner (26/20) adapted for injecting said pumping beam into the core (24) and/or into the first cladding (24). Claim(s) 2, 4-5, 7, 9-10, and 15 are rejected under 35 U.S.C. 103 as being unpatentable over Khitrov ‘761 in view of Chen US 2010/0195194, herein after referred to as Chen ‘194. Regarding claim 2, Khitrov ‘761 further discloses bending losses for the fundamental mode less than 0.5 dB/m (Paragraph 24, losses less than 0.01dB/m), but not that the bending diameter is comprised between 10 cm and 20 cm (Paragraph 21 discloses 8 cm). In the same field of endeavor, Chen ‘194 discloses very large mode area single-mode amplifying optical fiber (10, Figure 16B, Paragraphs 101-110) having a bending diameter to be between 10 cm and 20 cm (Table 2). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention for the very large mode area single-mode amplifying optical fiber of Khitrov ‘761 to have a bending diameter between 10 cm and 20 cm as taught by Chen as there does not appear to be a technical different between with a larger diameter and the it would have been obvious to try a slightly larger diameter as taught by Chen ‘194 for the purpose of use in high optical power fiber based systems (Abstract). Regarding claim 4, Khitrov ‘761 does not specifically discloses that the very large mode area single-mode amplifying optical fiber presents an effective area greater than 450 micrometers µm2. In the same field of endeavor, Chen ‘194 discloses a very large mode area single-mode amplifying optical fiber (10, Figure 16B, Paragraphs 101-110) presents an effective area greater than 450 micrometers µm2 (Paragraph 52). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention for the very large mode area single-mode amplifying optical fiber of Khitrov ‘761 to presents an effective area greater than 450 micrometers µm2 as taught by Chen ‘194 for the purpose of use in high optical power fiber-based systems (Abstract). Regarding claim 5, Chen ‘761 further discloses that the wherein the core (20) and a first glass (cladding layers) are based on silica glass or on fluoride glass or on chalcogenide glass or on phosphate glass (Paragraph 67). Regarding claim 7, Chen ‘761 further discloses that the core (20) presents a flat-top or a parabolic refractive index profile (Figure 16A), or wherein the core (20) comprises a pedestal (32R) surrounding a central part of the core (20), the pedestal (32R) having a refractive index lower than the central part of the core (20) and higher than the first glass (Paragraphs 86-97). Regarding claim 9, Chen ‘761 further discloses that at least one glassy cladding (Figures 16A-B) comprises a second cladding (multiple claddings shown) arranged around the first cladding (32), the second cladding (40) having a lower refractive index than the first glass (Paragraphs 86-97). Regarding claim 10, Chen ‘761 further discloses that the second cladding (40) is selected from an all-solid cladding made of a second glass or an air cladding and a solid cladding made of a second glass (Paragraph 67-69), the air cladding being arranged between the first cladding and the solid cladding made of the second glass (Paragraph 67-69). Regarding claim 11, Chen ‘761 further disclose a polymer or metal cladding around said at least one glassy cladding (Paragraph 98-oil on outer cladding). Regarding claim 15, Khitrov ‘761 further discloses that the very large mode area single-mode amplifying optical fiber (Figure 2) being spooled with a bending diameter less than 30 cm and the fiber laser (Paragraph 21) further comprising a light source (16) generating a source beam to be amplified and at least one mirror (within laser 16) at a first end of the very large mode area single-mode amplifying optical fiber (Figure 1). Chen ‘761 further teaches a second mirror at a second end of the very large mode area single-mode amplifying optical fiber (Figure 20). Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to JESSICA S MANNO whose telephone number is (571)272-2339. The examiner can normally be reached Monday-Friday. 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, Kiesha Bryant can be reached at 571-272-3606. 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. /JESSICA S MANNO/SPE, Art Unit 2898
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Prosecution Timeline

May 23, 2023
Application Filed
Jan 07, 2026
Non-Final Rejection — §103, §112 (current)

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Prosecution Projections

1-2
Expected OA Rounds
72%
Grant Probability
96%
With Interview (+24.3%)
2y 10m
Median Time to Grant
Low
PTA Risk
Based on 197 resolved cases by this examiner. Grant probability derived from career allow rate.

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