DETAILED ACTION
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 .
Response to Amendment
Applicant’s Amendment filed December 16, 2025 has been fully considered and entered.
Inventorship
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claim Rejections - 35 USC § 102
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
Claims 1-8, 16-17, and 19 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Hayashi et al. (“Numerical modeling of a hybrid hollow-core fiber for enhanced mid-infrared guidance”, Vol. 29, No. 11, 24 May 2021, Optics Express, pages 17042-17052; cited on the IDS filed September 15, 2023; hereafter Hayashi).
Regarding claims 1-6, 8, 16-17, and 19; Hayashi discloses a hollow-core optical fiber (see Figure 1 on page 17044) comprising:
a hollow core extending along a central longitudinal axis of the hollow-core optical fiber (hollow core comprising air; see Figure 1);
a substrate (substrate; see annotated Figure 1 below), the substrate comprising a tubular shape and an inner surface (inner surface of substrate) surrounding the central longitudinal axis of the hollow-core optical fiber;
a first cladding (first cladding; see annotated Figure 1 below) positioned between the central longitudinal axis of the hollow-core optical fiber and the inner surface of the substrate, the first cladding surrounding the central longitudinal axis of the hollow-core optical fiber and comprising a Bragg structure (multilayer Bragg cladding, comprising alternating layers of polymer or glass with a different refractive index and glass; see Figure 1), the Bragg structure configured to provide a photonic bandgap operable to confine an optical signal with a wavelength λ propagating in the hollow core of the hollow-core optical fiber (see section 2 titled “Hybrid hollow-core fiber design” on pages 17043-17044), the Bragg structure further configured to provide an anti-resonant effect at the wavelength λ, the anti-resonant effect operable to confine the optical signal at the wavelength λ in the hollow core of the hollow-core optical fiber (as explained in paragraph 71 of the present application, the anti-resonant effect may be satisfied by a material having a thickness given by Equation 1:
t
A
R
=
(
2
m
-
1
)
λ
(
4
(
n
2
-
1
)
1
2
)
, where m is an integer that is greater than or equal to 1, therefore when m = 1, equation 1 becomes:
t
A
R
=
λ
(
4
(
n
2
-
1
)
1
2
)
=
λ
4
∙
1
n
2
-
1
, and Hayashi et al. discloses that for the multilayer Bragg structure, the thickness is calculated with an approximated quart-wave condition using equation (2) of Hayashi, which is:
t
i
=
λ
4
∙
1
n
i
2
-
1
, and thus Hayashi et al. does disclose that the Bragg structure is configured to provide an anti-resonant effect at the wavelength λ; see section 2 of Hayashi et al.); and
a second cladding (second cladding; see Figure 1 annotated below) positioned between the central longitudinal axis of the hollow-core optical fiber and the inner surface of the substrate, the second cladding surrounding the central longitudinal axis of the hollow-core optical fiber and comprising a plurality of cladding elements (cladding elements; see annotated Figure 1 below), the plurality of cladding elements configured to provide an anti-resonant effect at the wavelength λ, the anti-resonant effect operable to confine the optical signal at the wavelength λ in the hollow core of the hollow-core optical fiber (see section 2 titled “Hybrid hollow-core fiber design” on pages 17043-17044);
wherein the second cladding (second cladding) is positioned between the first cladding (first cladding) and the central longitudinal axis of the hollow-core optical fiber (see Figure 1, annotated below);
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wherein the first cladding (first cladding) is in direct contact with the second cladding (second cladding; see Figure 1 annotated above);
wherein the first cladding (first cladding) is in direct contact with the inner surface of the substrate (inner surface of substrate; see Figure 1 annotated above);
wherein the Bragg structure comprises alternating concentric first layers (glass layers; see Figure 1) and second layers (polymer or glass layers with a different refractive index), the first layers comprising a first refractive index at the wavelength λ and the second layers comprising a second refractive index at the wavelength λ, the second refractive index differing from the first refractive index (see Figure 1; see section 2, the Bragg cladding can be formed by a multilayer structure composed of two dielectric materials with different refractive index, such as glass/polymer, undoped/doped glass, or glass/air layers created by spacers or rings of concentric air holes”);
wherein the Bragg structure comprises 3 or more first layers (see Figure 1);
wherein the Bragg structure comprises 30 or fewer first layers (see Figure 1; see Tables 1 and 2);
wherein each first layer (glass layer) has a thickness from 0.1 μm to 4.0 μm (see Table 1 on page 17046);
wherein each cladding element (cladding elements; see Figure 1 annotated above) is spaced apart from adjacent cladding elements in a circumferential direction about the central longitudinal axis;
wherein each of the plurality of cladding elements (cladding elements; see Figure 1 annotated above) extends in a direction parallel to the central longitudinal axis of the hollow-core optical fiber and each of the plurality of cladding elements comprises a capillary; and
wherein the wavelength λ is in a range from 350 nm to 8000 nm (5 μm – 10.6 μm; see the abstract).
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 9-11 and 20 are rejected under 35 U.S.C. 103 as being unpatentable over Hayashi et al. (“Numerical modeling of a hybrid hollow-core fiber for enhanced mid-infrared guidance”, Vol. 29, No. 11, 24 May 2021, Optics Express, pages 17042-17052; cited on the IDS filed September 15, 2023; hereafter Hayashi).
Regarding claims 9-11; Hayashi disclose the hollo-core optical fiber of claim 9 as discussed above, wherein the first layers are interconnected (see Figure 1), but Hayashi does not explicitly state:
the difference between the first refractive index and the second refractive index is greater than 0.10;
wherein the first layers comprise glass and the second layers comprise air.
Hayashi does teach that Bragg cladding (first cladding) may be formed by a multilayer structure composed of two dielectric materials with different refractive index, such as glass/polymer, undoped/doped glass, or glass/air layers created by spacers or rings of concentric air holes (see section 2). The examiner notes that glass and air have different refractive index values with a difference greater than 0.10. Before the effective filing date of the present invention, a person of ordinary skill in the art would have found it obvious to form the alternating layers from glass and air in alternative to glass and doped glass/polymer, as explicitly suggested by Hayashi in section 2, and thus would have found it obvious to form the first cladding with a difference between the first refractive index and the second refractive index that is greater than 0.10.
Regarding claim 20; Hayashi discloses the hollow-core optical fiber of claim 1 (see the rejection of claim 1 above), wherein the first cladding and the second cladding are configured such that a confinement loss of a fundamental mode of the optical signal propagating in the hollow-core optical fiber is minimal at the wavelength λ, but does not specifically disclose that the loss is less than 10-2 dB/km. Hayashi does teaches that the loss (α in dB/km) may be calculated using equation 3 for a desired wavelength (λ; see page 17044), wherein the diameter, constituent materials, thickness of the inner tubes, number of bilayers, and thicknesses of the layers determine a complex refractive index, and the imaginary part (κ) of the complex refractive index is used to calculate the loss (α). Thus, before the effective filing date of the present invention, a person of ordinary skill in the art would have found it obvious to adjust the diameter, constituent materials, thickness of the inner tubes, number of bilayers, and thicknesses of the layers to obtain any desired loss for a particular wavelength, as suggested by the teachings of Hayashi, including a minimize less that is less than 10-2 dB/km for the purpose of improving optical coupling efficiency of the resulting optical fiber.
Claims 12-15 are rejected under 35 U.S.C. 103 as being unpatentable over Hayashi et al. (“Numerical modeling of a hybrid hollow-core fiber for enhanced mid-infrared guidance”, Vol. 29, No. 11, 24 May 2021, Optics Express, pages 17042-17052; cited on the IDS filed September 15, 2023; hereafter Hayashi) in view of Fink et al. (US 7,310,466 B2).
Regarding claims 12 and 13; Hayashi teaches or suggests the hollow-core optical fiber of claim 11, as applied above, but does not disclose that the first layers are interconnected by a plurality of ribs extending parallel to the central longitudinal axis of the hollow-core optical fiber.
Hayashi does teach that the first cladding (multilayer Bragg cladding; see Figure 1 of Hayashi) may be formed by alternating layers of glass and air (see section 2 of Hayashi and the rejection of claims 9-11 above), and that the alternating layers have a thickness between 0.1 μm and 5 μm (see the thickness in Tables 1 and 2). Fink et al. teaches that a Bragg cladding (1520) of a hollow core (1510) fiber (1550; see Figure 15B) may be formed by alternating layers of a first material and air (1540), wherein a plurality of ribs (1581) are provided as spacers to maintain alternating air layers.
Before the effective filing date of the present invention, a person of ordinary skill in the art would have found it obvious to form the multilayer Bragg cladding (first cladding) of Hayashi with alternating layers of glass and air, and to further interconnect the first layers by a plurality of ribs extending parallel to the central longitudinal axis of the hollow-core optical fiber for the purpose of maintaining a desired gap and thereby a desired thickness of the air layers, as suggested by the teachings of Fink et al., wherein the thickness of the rods is between 0.1 μm and 5 μm, thereby providing air layers with a thickness in the range disclosed by Hayashi.
Regarding claims 14 and 15; Hayashi teaches or suggests the hollow-core optical fiber of claim 11, as applied above, but does not disclose that the first layers are interconnected by a plurality of tubes extending parallel to the central longitudinal axis, wherein each of the plurality of tubes are positioned on radii of the hollow-core optical fiber that do not pass through the plurality of cladding elements.
Hayashi does teach that the first cladding (multilayer Bragg cladding; see Figure 1 of Hayashi) may be formed by alternating layers of glass and air (see section 2 of Hayashi and the rejection of claims 9-11 above). Fink et al. teaches that a Bragg cladding (1520) of a hollow core (1510) fiber (1500; see Figure 15A) may be formed by alternating layers of a first material and air (1540), wherein a plurality of tubes (1541) are provided as spacers to maintain alternating air layers, the tubes extending parallel to the longitudinal axis.
Thus, before the effective filing date of the present invention, a person of ordinary skill in the art would have found it obvious to provide a plurality of tubes in the invention of Hayashi, the first layers being interconnected by the plurality of tubes extending parallel to the central longitudinal axis, wherein each of the plurality of tubes are positioned on radii of the hollow-core optical fiber that do not pass through the plurality of cladding elements for the purpose of maintaining a desired thickness of the air layers, as suggested by the teachings of Fink et al.
Allowable Subject Matter
Claim 18 is objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
The following is a statement of reasons for the indication of allowable subject matter: The prior art of record, which is the most relevant prior art known, does not disclose or render obvious the hollow-core optical fiber defined by claim 18, wherein each of the plurality of cladding elements extends in a direction parallel to the central longitudinal axis of the hollow-core optical fiber and each of the plurality of cladding elements comprises a glass sheet configured as a spiral in combination with all of the limitations of base claim 1.
Response to Arguments
Applicant's arguments filed December 16, 2025 have been fully considered but they are not persuasive.
Applicant argues that Hayashi fails to disclose a first cladding configured such that it confines light in the hollow core of the hollow-core optical fiber through both a photonic bandgap and anti-resonance.
The examiner disagrees. Annotated Figure 1, referenced in the rejection above is copied below for convenience.
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The first cladding labeled above is a multilayer Bragg structure. As explained by Hayashi (see section 2 and equation 2), “[f]or the multilayer Bragg structure, the position of the photonic bandgap must be tuned to be centered around the target λ by selecting the thickness of the glass and polymer layers (tg and tp), which can be calculated with an approximated quarter-wave condition (Eq. (2))”, wherein equation (2) states:
t
i
=
λ
4
∙
1
n
i
2
-
1
This quarter-wave condition is the condition required to provide an anti-resonant effect as detailed in the present specification. Paragraph 71 of the present application teaches that “[t]he anti-resonant effect may, in one embodiment, be satisfied by a material having a thickness given by Equation 1”, wherein equation 1 states:
t
A
R
=
(
2
m
-
1
)
λ
(
4
(
n
2
-
1
)
1
2
)
, where m is an integer that is greater than or equal to 1.
Thus, when m = 1, equation 1 becomes:
t
A
R
=
λ
(
4
(
n
2
-
1
)
1
2
)
=
λ
4
∙
1
n
2
-
1
Therefore, equation (2) of Hayashi et al. is in agreement with equation (1) of the present application, which is the condition required to ensure that the first cladding has an anti-resonant effect.
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.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to MICHELLE R CONNELLY whose telephone number is (571)272-2345. The examiner can normally be reached Monday-Friday, 9 AM to 5 PM.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Uyen-Chau Le can be reached at 571-272-2397. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/MICHELLE R CONNELLY/Primary Examiner, Art Unit 2874