DETAILED ACTION
This office action is in response to applicant’s remarks filed on October 15, 2025. Claims 1-6 and 19 are under consideration.
Claim Rejections - 35 USC § 102
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 1-2 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by He et al. (WO 2020/073707 A1, herein “He”).
Regarding claim 1, He discloses a mode field adapter, comprising:
a first port that includes a first collimating lens (200) having a first focal length and that is configured to receive a first optical fiber (100) having a first mode field diameter (fiber 100 is a single mode fiber); and
a second port that includes a second collimating lens (210) having a second focal length different from the first focal length (the mode size of the single mode fiber and the large mode fiber are different which requires the focal length of the second collimating lens 210 to be different from the focal length of the first collimating lens),
wherein the first collimating lens is configured to receive a diverging optical beam from the first optical fiber and generate an expanded optical beam therefrom (Para [0049] and see ray trace of Fig. 1 showing the collimated and expanded beam emitting from collimating lens 200), and
the second collimating lens (210) is configured to receive at least a portion of the expanded optical beam, generate a first converging optical beam therefrom, and transmit the first converging optical beam into the second optical fiber (110).
The examiner notes, the single mode fiber 100 is considered “a first port” in that it receives a signal from a laser source and output the signal to a collimating lens. Similarly, the large mode fiber 120 is considered “a second port” as it receives expanded optical beam and output to a predetermined destination.
Claim 2. He discloses the first focal length and the second focal length are selected so that a ratio of the first focal length to the second focal length is substantially the same as the ratio of the first mode field diameter to the second mode field diameter (this ratio f1/f2 = d1/d2 is the inverse of f2/f1 = d2/d1 which relates to the magnification of the mode field expander, He Para [0049]).
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 3 is rejected under 35 U.S.C. 103 as being unpatentable over He in view of (meisuoptics.com, The Basic Principle of Fiber Collimator, earliest capture by the Wayback Machine is January 20, 2021).
He discloses the invention of Claim 3, but He does not explicitly disclose the first optical fiber includes a first end face, the second optical fiber includes a second end face, the first port is configured so that a distance between the first collimating lens and the first end face is substantially the same as the first focal length, and the second port is configured so that the distance between the second collimating lens and the second end face is substantially the same as the second focal length..
Meisu Optics teaches in blog post The Basic Principle of Fiber Collimator under section 1. The principle of fiber collimator, that the fiber end face is required to be placed at the focal point of the collimating lens to collimate the beam. This is also known as “the working distance” of the collimator, L. The working distance L along with the design requirements, are used to calculate the spot size of the beam and then calculate the point accuracy of the collimator.
It would have been obvious to one having ordinary skill in the art to recognize the teaching of Meisu Optics is the foundational principle of collimating light from an optical fiber using a collimating lens, which is inherent in the invention to He. One would be motivated to place the first port at a distance between the first collimating lens and the first fiber end face at the focal length of the first collimating lens so that the optical beam from the fiber can be collimated. Similarly, placing the second port at a distance between the second collimating lens and the second fiber end face at the focal length of the second collimating lens so that the optical beam from can collimate the optical beam.
Claims 4-5 are rejected under 35 U.S.C. 103 as being unpatentable over He in view of Tanaka et al. (US 2023/0010259 A1, herein “Tanaka”).
He discloses the invention of claim 1, but does not teach the invention as recited in claim 4 and 5.
Tanaka teaches wavelength multiplexing device comprising a first port (10) that includes a first collimating lens (12) configured to receive a first optical fiber (11 in Fig. 2), a plurality of filters (40[1]…40[M]) configured to define an optical path by each filter receiving the optical beam, transmitting a predetermined portion of the optical beam, and reflecting a remaining portion of the optical beam along the optical path (Para [0064]-[0065]), wherein
the second port (20[1]) is one of a plurality of second ports (20[2]…20[M]) each including a respective second collimating lens (22) having a focal length (G) (Fig. 3 shows the second collimator (20[1]- 20[12]),
the second optical fiber is one of a plurality of second optical fibers (21), and
the second collimating lens (22) of each second port is configured to receive the predetermined portion of the expanded optical beam transmitted from a respective filter (40[1]…40[M]). See Fig. 1.
Tanaka further teaches an additional first port (80 in Fig. 26) including another first collimating lens (Fig. 2 shows the details of the collimating lens of the first port) having a focal length G, wherein
the first optical fiber is one of a plurality of first optical fibers (see the fiber tail at port 80 not labeled),
the plurality of filters includes (40[1]…40[M]) includes a last filter (40[12]) that reflects the remaining portion of the expanded optical beam along the optical path after the expanded optical beam has been reflected by each of the other filters (Para [0064]-[0065]),
the first collimating lens of the additional first port (80) is configured to receive the remaining portion of the expanded optical beam reflected from the last filter, generate a second converging optical beam therefrom, and transmit the second converging optical beam into the other first optical fiber.
It would have been obvious to one having ordinary skill in the art to recognize beam expander of He’s invention can be modified and scalable to be employed in the multiplexer-demultiplex as demonstrated by Tanaka. The first port of He wherein single mode fiber (100) and collimating lens (200) having a first focal length can be designed to fit in the ferrule (13) as shown by Tanaka. The second port of He wherein the large mode fiber (110) and collimating lens (210) having a second focal length different from the first focal length can be designed to fit in the ferrule (23) as shown by Tanaka. The resulting modification would by an input of single mode fiber sending a small mode field diameter beam to be expanded by the plurality of second ports receiving the expanded beam from the plurality of filters, wherein the filters would reflect the undesired band to the subsequent plurality of second ports and transmit the desired band along the optical path, as shown in the ray trace diagrams. One would be motivated to employ the thin-film filter wavelength division multiplexing add-drop modules of Tanaka to take advantage of the miniaturization of the WDM module and reduced optical alignment sensitivity.
Claims 6 and 19 are rejected under 35 U.S.C. 103 as being unpatentable over He in view of Faircloth et al. (WO-2019/117872 A1, herein “Faircloth”).
Regarding claim 6, He discloses the invention of claim 1, but does not disclose the first optical fiber is a hollow core optical fiber and the second optical fiber is a solid core optical fiber.
Faircloth teaches a mode field expander (Fig. 1) wherein the input fiber (102) has a smaller core size (200 micron) that the output fiber (103), 400 micron (Para [0041]). The beam expander also has a first collimating lens and the second collimating lens wherein the collimating lenses have different focal length (different fiber core sizes would require different focal lengths). Faircloth further discloses the optical fibers of the beam expander in Fig. 1 can be any of the known fibers such as single mode and/or multimode, solid cores or hollow core fibers (Para [0080]). It would have been obvious to one having ordinary skill in the art to recognize hollow core fibers would be preferred to be the first optical fiber that is coupled the laser light source since hollow core fibers have been demonstrated to be capable of high power laser coupling and mode filtering characteristics.
Regarding claim 19, He teaches the ratio of the effective focal length of the converging lens 210 to the effective focal length of the collimating lens 200 is equal to the ratio of the mode field radius (W1) at SMF to the mode field radiusW2 at LMAF (Para [0049]). He in view of Faircloth does not explicitly teach the focal length ratio of the first collimating lens and the second collimating lens is from 1.5 to 6.0. It would have been obvious to one of ordinary skill in the art at the effective filing date of the invention to optimize the focal length ratio with respect to the mode field radius W1 and W2 for optimal coupling efficiency, 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, In re Aller, 105 USPQ 233 (C.C.P.A. 1955).
Response to Arguments
Applicant's arguments filed October 15, 2025 have been fully considered but they are not persuasive.
Applicant argues He does not anticipate “a first port” or “a second port” as recited in claim 1 (Remarks, page 10).
The examiner respectfully disagrees. He teaches the microstructure optical fiber device includes a single-mode optical fiber serving as an optical fiber input end, an optical fiber integration module, a large mode field optical fiber as an optical fiber output end, wherein the single mode optical fiber and the optical fiber integration module, and the large mode field optical fiber are arranged inside the encapsulation housing (He: Para [0034]). Therefore, the examiner considers the optical fiber input end to be a “first port” of the encapsulated housing and the optical fiber output end to be a “second port” of the encapsulated housing, wherein the first port is configured to receive a first optical fiber having a first mode field diameter and the second port is configured to receive a second optical fiber having a second mode field diameter different from the first mode field diameter (mode field radius W1 is converted to mode field radius W2, Para [0049]).
Applicant argues the prior art to Meisu Optics does not remedy the deficiency of He for failing to teach the “first port” and the “second port”.
The examiner respectfully disagrees. Prior art to Meisu Optics was provided to teach basic optical principle of “the working distance”—the length L between the optical fiber end face and the focal point of the collimator. Meisu was not applied to the rejection of claim 3 for teach the first and second port. See response to argument A.
Applicant argues He in view of Tanaka does not teach “a plurality of second optical fibers each having the second mode field diameter different from the first mode field diameter.”
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The examiner respectfully disagrees. Fig. 13 isolates the m wavelength selective filter 40 (m) disclosing the beam diameter D1 on one end of the filter 40(m) is different from the beam diameter D2 on the opposite end of the filter. By modifying the primary reference of He with the filters 40(1) to 40 (m) of Tanaka, one can expand the mode field diameter from the input relative to the output end of the plurality of inputs and the plurality of outputs to maximize coupling efficiency.
Applicant argues Faircloth is silent to the specific combination of a hollow core and solid core fibers. Therefore, Faircloth could not possibly teach to modify the teachings of He such that the first optical fiber is a hollow core and the second optical fiber is a solid core without hindsight.
The examiner respectfully disagrees. Faircloth teaches coupling of two optical fibers at the input and at the output (Fig. 1) wherein Faircloth teaches any of the optical fibers are compatible to the assembly shown in Fig. 1 wherein “the optical fibers may be entirely constructed of glass, hollow core photonic crystal, and/or solid core photonic crystals” (Para [0080]). Therefore, the examiner considers Faircloth contemplated the combination of hollow core fiber to solid core fiber wherein a high power laser would transmit to the hollow core fiber which has low nonlinearity and high damage thresholds for efficient and stable beam delivery.
For the reasons above, the examiner maintains the grounds of rejection.
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 Erin D Chiem whose telephone number is (571)272-3102. The examiner can normally be reached 10 am - 6 pm.
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/ERIN D CHIEM/Examiner, Art Unit 2874
/THOMAS A HOLLWEG/Supervisory Patent Examiner, Art Unit 2874
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