DETAILED ACTION
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on June 11, 2026 has been entered. Claims 1-5 and 19 are under consideration.
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 1-2 are rejected under 35 U.S.C. 103 as being unpatentable over He et al. (WO 2020/073707 A1, herein “He”) in view of Abdolvand et al. (WO 2024/120709 A1, herein “Abdolvand”).
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;
a first optical fiber (100) having a first mode field diameter (fiber 100 is a single mode fiber) received by the first port; 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),
a second optical fiber (110) having a second mode field diameter different from the first mode field diameter (“large mode area fiber 110”) different from the first mode field diameter (“singlemode fiber 100”) and received by the second port,
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).
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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.
However, He does not disclose the first optical fiber being a hollow core optical fiber and He does not disclose the second optical fiber being a solid core optical fiber.
Abdolvand teaches a broadband radiation source wherein a drive laser (DL) emits drive radiation to the first port, hollow core fiber (HCF), and further couples to the second port solid core fiber (SCF) and output the broadband radiation, supercontinuum SCout (Para [000113]). Abdolvand further teaches the hollow core fiber and the solid core fiber may be coupled via free space optics or they may be spliced directly to one another (Para [00015]). As for the limitation—the first optical fiber being a hollow core optical fiber of a fronthaul network—and—the second optical fiber being a solid core optical fiber of a drop cable—the examiner considers the “fronthaul network” and the “drop cable” as intended use. There is no structural limitation pertaining to the fronthaul network and the drop cable that would preclude the hollow core fiber and solid core fiber of Abdolvand from being coupled in another optical architecture.
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It would have been obvious to one having ordinary skill at the time of filing to recognize a mode field adapter that employs hollow core fiber that couples to solid core fiber would generate continuous high capacity broadband spectrum (i.e., continuum) which in turn would generate a large amount of heat. Abdolvand further teaches the damage tolerance of the hollow core fiber is higher than the damage tolerance of the solid core fiber such that when spliced, adaptors may be provided between the fibers for mode-filling the diameters of each successive fiber (Paras [000102] and [000121]). One would be motivated to employ hollow core fiber and solid core fiber in an optical system to generate high capacity broadband spectrum while avoiding damage to the optical fiber by selecting high damage tolerance hollow core photonic bandgap fiber.
Claim 2. He further 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 19. He / Abdolvand teach the invention of claim 1, but He / Abdolvand do not explicitly teach the focal length ratio of the first collimating lens and the second collimating lens is from 1.5 to 6.0.
However, 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]). 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).
Claim 3 is rejected under 35 U.S.C. 103 as being unpatentable over He in view of Abdolvand (herein “He / Abdolvand”) as applied to claim 1 above, and further in view of (meisuoptics.com, The Basic Principle of Fiber Collimator, earliest capture by the Wayback Machine is January 20, 2021).
He / Abdolvand teach the invention of Claim 1, 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 / Abdolvand. 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 / Abdolvand as applied to claim 1 above, and further 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 / Abdolvand’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.
Response to Arguments
Applicant’s arguments with respect to claims 1-5 and 19 have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument.
Conclusion
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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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Thomas A. Hollweg can be reached at (571) 270-1739. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/ERIN D CHIEM/Examiner, Art Unit 2874
/THOMAS A HOLLWEG/Supervisory Patent Examiner, Art Unit 2874
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