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 on July 24, 2026 has been entered.
Applicant’s amendment overcome the 35 U.S.C 112(b) rejection of claims 10, 11, 14 and 30.
Currently claims 1-31 are pending.
Response to Arguments
Applicant's arguments filed on 07/24/2026 have been fully considered but they are not persuasive.
Applicant argues that the newly amended limitation are patentable over the cited sections of the applied reference. Applicant also points out under “Statement Regarding Substance of Interview” that “The Examiner agreed that the proposed amendments, substantially included in this response, overcome the applied references.”.
In response it is respectfully pointed out to applicant that in the “Interview Summary” mailed on 07/13/2026, the examiner clearly stated that the proposed amendment would overcome the anticipation rejection but an obviousness rejection would be applicable based on the disclosure of the current reference used in the rejection. Further, a new reference US 2023/0213703 A1 was also applied to further strengthen the position taken by the examiner. Therefore, the current rejection is made under obviousness and the newly amended limitation are not patentable over the applied reference Bian.
Examiner’s Note
The examiner has pointed out particular references contained in the prior art of record within the body of the action for the convenience of the applicant. Although the specified citations are representative of the teachings in the art and are applied to the specific limitations within the individual claim, other passages and figures may apply. Applicant, in preparing response should consider fully the entire reference as potentially teaching all or part of the claimed invention, as well as the context of the passage as taught by the prior art or discussed by the examiner.
In addition, the functional recitation in the claims (e.g. "configured to" or "adapted to" or the like) that does not limit a claim limitation to a particular structure does not limit the scope of the claim. It has been held that the recitation that an element is "adapted to", "configured to", "designed to", or "operable to" perform a function is not a positive limitation but only requires the ability to so perform and may not constitute a limitation in a patentable sense. In re Hutchinson, 69 USPQ 139. (See MPEP 2111.04); see also In In re Giannelli, 739 F.3d 1375, 1378, 109 USPQ2d 1333, 1336 (Fed. Cir. 2014).
Also, it should be noted that it has been held that a recitation with respect to the manner in which a claimed device is intended to be employed does not differentiate the claimed device from a prior art apparatus satisfying the claimed structural limitations Ex-parte Masham 2 USPQ2d 1647 1987).
The claimed system in the instant application is capable of performing the claimed functionality, as is the prior art used in the present office action. The Examiner notes that where the patent office has reason to believe that a functional limitation asserted to be critical for establishing novelty in the claimed subject matter may, in fact, be an inherent characteristic of the prior art, it possesses the authority to require the applicant to prove that the subject matter shown to be in the prior art does not possess the characteristic relied on. In re Swinehart and sfiligoj, 169 USPQ 226 (C.C.P.A. 1971).
Claim Rejections - 35 USC § 103
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 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.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
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.
Claims 1-4, 7-13, 15, 16, 22-27 and 29 are rejected under 35 U.S.C. 103 as being unpatentable over Bian, US 2023/0314706 A1 alone or in view of Nesic et al., (hereinafter Nesic), US 2023/0213703 A1.
As to claim 1, Bian discloses and shows in Figures, an interlayer transition coupling structure, comprising:
a first lateral interface and a second lateral interface that are perpendicular to a first lateral axis and define a lengthwise dimension of the interlayer transition coupling structure (Figs. 1A, 1B; para. [0015]-[0019]; ends facets of the first and second waveguides cores (elements 111/121) define the “lengthwise” direction; The waveguides extend from left to right in Fig. 1A, so their input/output facets are the first and second lateral interfaces that are perpendicular to a first lateral axis);
a first lateral side and a second lateral side that are perpendicular to a second lateral axis and define a widthwise dimension of the interlayer transition coupling structure (Fig. 1A; the top/bottom boundaries of the waveguide cores define the widthwise dimension);
a cladding layer (para [0017]-[0021]; silicon dioxide or similar surrounds each waveguide core);
a first waveguide layer arranged in the cladding layer and configured to guide a first optical signal lengthwise along at least a first portion of the interlayer transition coupling structure (first waveguide core 110 in cladding 105; para [0017]-[00119]; the primary waveguide core 110 carries light in the first layer); and
a second waveguide layer arranged in the cladding layer and configured to guide a second optical signal lengthwise along at least a second portion of the interlayer transition coupling structure (second waveguide core 120 in cladding 105; para [0018]-[0019],
wherein the first waveguide layer and the second waveguide layer are spatially
overlapped in a vertical direction in a third portion of the interlayer transition coupling structure,
wherein the first waveguide layer and the second waveguide layer are optically coupled in the vertical direction to transfer an optical signal between the first waveguide layer and the second waveguide layer, (para. [0019]; first end portion 111 overlays second end portion 121; coupler 155 includes an additional waveguide core 150 vertically between and physically separating them; the stacked mini-waveguide 150 mediates evanescent coupling between the two main waveguides),
wherein the first waveguide layer includes:
a first constant width section that extends lengthwise, along a first center axis,
from the first lateral interface toward the second lateral interface, wherein the first
constant width section has a first constant width (Fig. 1B; element 112; main body of first waveguide core with uniform width);
a first tapered width section that extends lengthwise, along the first center axis,
from the first constant width section toward the second lateral interface, wherein the first
tapered width section has a first tapered width that tapers from the first constant width
section to a first tip section having a first tip width (para. [0039]; “width of the first end portion 111 can taper down…essentially linearly” to a minimum width); and
a first displacing waveguide section that extends from the first tip section to the
second lateral interface, wherein the first displacing waveguide section has a first
displaced waveguide tip, arranged at the second lateral interface, that has a first lateral
offset distance from the first center axis (para. [0043]-[0044]; coupler geometry where the overlap area between stacked cores decreases along the length (i.e., the mini-waveguide tip displaces laterally away until no overlap; As the mini-waveguide 150 extends to the output side, it eventually stops overlapping the other waveguide, providing the claimed displacement),
wherein the second waveguide layer includes:
a second constant width section that extends lengthwise, along a second center
axis, from the second lateral interface toward the first lateral interface, wherein the
second constant width section has a second constant width (Fig. 1B, element 112; main body of second waveguide core with uniform width); and
a second tapered width section that extends lengthwise, along the second center
axis, from the second constant width section toward the first lateral interface, wherein the second tapered width section has a second tapered width that tapers from the second constant width section to a second tip section having a second tip width (para. [0039]-[0041]; “width of the second end portion 121…tapers down ..essentially linearly.”).
Bian does not explicitly disclose the limitation such as, “wherein the second tip section is not spatially overlapped with the first constant width section”.
However, Bian teaches that the waveguide shapes and overlap geometry are selected to achieve mode matching and reduce signal loss, and that the geometry may vary depending on the separation distance and desired coupling behavior. See ¶¶ [0013], [0019], [0037]-[0044], [0056].
Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to arrange the tapered tip section of the second waveguide core so that it is not spatially overlapped with the constant-width section of the first waveguide core as a predictable design variation to control coupling geometry, manage mode matching, and reduce unwanted interaction between non-coupling portions of the waveguides. Under KSR v. Teleflex, 550 U.S. 398 (2007), a claim is unpatentable when it is directed to a predictable variation of known elements yielding no more than the expected results. The claimed non-overlap condition is such a predictable geometric adjustment in the context of Bian’s disclosed interlayer coupling structure.
Further, Nesic teaches waveguide regions that initially overlap or are close together and then become spatially disjoint after gradual divergence. See ¶¶ [0088]-[0093], [0099]-[0101].
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Bian’s interlayer waveguide coupling geometry in view of Nesic to provide a second tip section that is not spatially overlapped with the constant-width portion of the first waveguide mode path, as a predictable variation to achieve controlled adiabatic coupling/decoupling and low-loss signal transfer.
Under KSR v. Teleflex, 550 U.S. 398 (2007), combining familiar elements according to known methods to yield predictable results is obvious. The claimed non-overlapping tip arrangement and gradual displacement path would have been a predictable design variation in view of the combined teachings.
As to claim 2, Bian discloses the interlayer transition coupling structure of claim 1, wherein the first displacing waveguide section extends from the first tip section to the second lateral interface in both a first lateral direction that is parallel to the first lateral axis and a second lateral direction that is parallel to the second lateral axis (para. [0043]; the mini-waveguide 150 can extend laterally both along and across the primary lengthwise axis to minimize overlap. Fig. 1A shows the mini-waveguide 150 shifting laterally and longitudinally to decouple).
As to claim 3, Bian discloses the interlayer transition coupling structure of claim 1, wherein the first displacing waveguide section is a straight waveguide that extends from the first tip section to the second lateral interface in both a first lateral direction that is parallel to the first lateral axis and a second lateral direction that is parallel to the second lateral axis (Fig. 1B; para. [0043]-[0044]; coupler 155 can be straight).
As to claim 4, Bian discloses the interlayer transition coupling structure of claim 1, wherein the first displacing waveguide section is a curved waveguide having one or more curves, wherein the first displacing waveguide section extends in a first lateral direction that is parallel to the first lateral axis and in a second lateral direction that is parallel to the second lateral axis (Para. [0043]; “optical tapering could be exponential” Figs. 1C-1D illustrate non-linear and curved transitions 111, 121).
As to claim 7, Bian discloses the interlayer transition coupling structure of claim 1, wherein the first constant width section and the second tapered width section are spatially overlapped in the vertical direction (Figs. 1B-1C; main body 112 of the first waveguide sits immediately beneath tapered portion 121 of the second waveguide).
As to claim 8, Bian discloses the interlayer transition coupling structure of claim 1, wherein the second constant width section and the first tapered width section are spatially overlapped in the vertical direction (Figs. 1B-1C, element 122 beneath tapered end 111).
As to claim 9, Bian discloses the interlayer transition coupling structure of claim 1, wherein the first constant width section and the second tapered width section are spatially overlapped in the vertical direction, wherein the second constant width section and the first tapered width section are spatially overlapped in the vertical direction, and
wherein a first lateral end portion of the first constant width section is spatially
overlapped with a second lateral end portion of the second constant width section (Fig. 1B; tip 111 overlaps main body 122; tip 121 overlaps main body 112; and main bodies 112/122 meet at a boundary).
As to claim 10, Bian discloses the interlayer transition coupling structure of claim 1, wherein a coupling portion of the first displacing waveguide section is spatially overlapped with the second constant width section, wherein an area of overlap between the coupling portion and the second constant width section in the vertical direction gradually decreases as the first displacing waveguide section extends from the first tip section toward the second lateral interface, and wherein the coupling portion is optically coupled to the second constant width section (para. [0043]; overlap area of mini-waveguide vs. main bodies gradually decrease toward output).
As to claim 11, Bian discloses the interlayer transition coupling structure of claim 10, wherein the first displaced waveguide tip and the second waveguide layer are not spatially overlapped in the vertical direction (para. [0043]; “and then into the other end portion…without exceeding loss” implies final tip 150 does not overlap second waveguide).
As to claim 12, Bian discloses the interlayer transition coupling structure of claim 1, wherein the first displacing waveguide section extends from the first tip section to the second lateral interface such that a spatial overlap between the first displacing waveguide section and the second constant width section gradually decreases (para. [0043]-[0044])
As to claim 13, Bian discloses the interlayer transition coupling structure of claim 1, wherein the first displacing waveguide section is configured to conduct the optical signal from a first region that is spatially overlapped with the second waveguide layer to a second region that is not spatially overlapped with the second waveguide layer (Figs. 1B-1E; initial mini-waveguide region overlaps both cores; final region overlaps neither).
As to claim 15, Bian discloses the interlayer transition coupling structure of claim 1, wherein the first center axis and the second center axis are colinear (Fig. 1B; waveguide cores 110/120 are aligned along same centerline in the coupling region).
As to claim 16, Bian discloses the interlayer transition coupling structure of claim 15, wherein the second tip section is spatially overlapped with the first constant width section (Fig. 1B; tip 121 overlaps main body 112).
As to claim 22, Bian discloses the interlayer transition coupling structure of claim 1, wherein the first waveguide layer and the second waveguide layer are spatially separated in the vertical direction by a portion of the cladding layer (paras. [0017]-[0021]; waveguide cores 110/120 are in different levels, separated by cladding layers).
As to claim 23, Bian discloses the interlayer transition coupling structure of claim 1, wherein the first waveguide layer and the second waveguide layer are optically coupled in the vertical direction by an evanescent-wave coupling to transfer an optical power between the first waveguide layer and the second waveguide layer (para. [0021]; “optical signal pass .. particularly…so that optical signals can pass .. where the propagation constant ….becomes the same” – describes evanescent coupling).
As to claim 24, Bian discloses the interlayer transition coupling structure of claim 23, wherein the first optical signal and the second optical signal are different optical signals having substantially equal effective propagation indices (para. [0023]; shapes are configured for mode matching so that the propagation constants are the same).
As to claim 25, Bian discloses the interlayer transition coupling structure of claim 1, wherein the first waveguide layer is made of a first waveguide material, and wherein the second waveguide layer is made of a second waveguide material that is different from the first waveguide material (para. [0021]; “first waveguide core 110, … and the second waveguide core 120 …. Can be made of the same or different waveguide core materials.”).
As to claim 26, Bian discloses the interlayer transition coupling structure of claim 1, wherein the first waveguide layer is a first waveguide core and the second waveguide layer is a second waveguide core (refers to first and second waveguide cores 110/120).
As to claim 27, Bian discloses the interlayer transition coupling structure of claim 1, wherein the first displacing waveguide section is configured to reduce at least one of:
a mode mismatch loss of the optical signal, which is transferred between the first
waveguide layer and the second waveguide layer,
a back reflection between the first waveguide layer and the second waveguide layer during transfer of the optical signal, or
a crosstalk between the first waveguide layer and the second waveguide layer during transfer of the optical signal (para. [0023]; “mode matching … so that optical signal pass … without exceeding …loss” which inherently reduces back-reflection and crosstalk).
As to claim 29, Bian discloses and shows in Figures, a multicore waveguide comprising:
a first lateral interface and a second lateral interface that are perpendicular to a first lateral axis and define a lengthwise dimension of the multicore waveguide (Figs. 1A, 1B; para. [0015]-[0019]; ends facets of the first and second waveguides cores (elements 111/121) define the “lengthwise” direction; The waveguides extend from left to right in Fig. 1A, so their input/output facets are the first and second lateral interfaces that are perpendicular to a first lateral axis);
a first lateral side and a second lateral side that are perpendicular to a second lateral axis and define a widthwise dimension of the multicore waveguide (Fig. 1A; the top/bottom boundaries of the waveguide cores define the widthwise dimension);
a cladding layer (para [0017]-[0021]; silicon dioxide or similar surrounds each waveguide core);
a first waveguide layer arranged in the cladding layer and configured to guide a first optical signal lengthwise along at least a first portion of the multicore waveguide (first waveguide core 110 in cladding 105; para [0017]-[00119]; the primary waveguide core 110 carries light in the first layer); and
a second waveguide layer arranged in the cladding layer and configured to guide a second optical signal lengthwise along at least a second portion of the multicore waveguide (second waveguide core 120 in cladding 105; para [0018]-[0019],
wherein the first waveguide layer and the second waveguide layer are spatially
overlapped in a vertical direction in a third portion of the multicore waveguide,
wherein the first waveguide layer and the second waveguide layer are optically coupled in the vertical direction to transfer an optical signal between the first waveguide layer and the second waveguide layer, (para. [0019]; first end portion 111 overlays second end portion 121; coupler 155 includes an additional waveguide core 150 vertically between and physically separating them; the stacked mini-waveguide 150 mediates evanescent coupling between the two main waveguides),
wherein the first waveguide layer includes:
a first constant width section that extends lengthwise, along a first center axis,
from the first lateral interface toward the second lateral interface, wherein the first
constant width section has a first constant width (Fig. 1B; element 112; main body of first waveguide core with uniform width);
a first tapered width section that extends lengthwise, along the first center axis,
from the first constant width section toward the second lateral interface, wherein the first
tapered width section has a first tapered width that tapers from the first constant width
section to a first tip section having a first tip width (para. [0039]; “width of the first end portion 111 can taper down…essentially linearly” to a minimum width); and
a first displacing waveguide section that extends from the first tip section to the
second lateral interface, wherein the first displacing waveguide section has a first
displaced waveguide tip, arranged at the second lateral interface, that has a first lateral
offset distance from the first center axis (para. [0043]-[0044]; coupler geometry where the overlap area between stacked cores decreases along the length (i.e., the mini-waveguide tip displaces laterally away until no overlap; As the mini-waveguide 150 extends to the output side, it eventually stops overlapping the other waveguide, providing the claimed displacement),
wherein the second waveguide layer includes:
a second constant width section that extends lengthwise, along a second center
axis, from the second lateral interface toward the first lateral interface, wherein the
second constant width section has a second constant width (Fig. 1B, element 112; main body of second waveguide core with uniform width); and
a second tapered width section that extends lengthwise, along the second center
axis, from the second constant width section toward the first lateral interface, wherein the second tapered width section has a second tapered width that tapers from the second constant width section to a second tip section having a second tip width (para. [0039]-[0041]; “width of the second end portion 121…tapers down ..essentially linearly.”).
Claim(s) 5, 6, 14, 17-21 and 28 are is/are rejected under 35 U.S.C. 103 as being unpatentable over unpatentable over Bian in view of CN 115793140A (hereinafter CN’140) (translation provided)
As to claims 5 and 6, Bian discloses the interlayer transition coupling structure of claim 1, wherein the first displacing waveguide section is a slanted waveguide that slants at an offset angle relative to the first center axis and extends from the first tip section at the offset angle toward the second lateral side (paras. [0014]-[0019], [0039]-[0044]; Figs. 1A-1E, 2A-2E, 3A-3G; teaches tapered end portions in vertically overlapped cores with a coupler (mini-waveguide cores 150/250/350) that facilitate gradual coupling/decoupling by varying overlap along the propagation direction. The overlap region “gradually decreases, inherently implying that the path of the coupling section has a lateral component with respect to the main axis; First “displacing waveguide section” corresponds to the portion that laterally relocates the optical mode path from overlapped to non-overlapped region).
Bian does not explicitly disclose the displacing section as a “slanted waveguide” at a defined “offset angle in a range of 0.5° to 20°.relative to the first center axis”.
CN’140 discloses an end-face coupler with a first tapered waveguide and a second tapered waveguide that are “reversely overlapped” and with one side of the second waveguide “far away” from the second tapered waveguide being matched to an external fiber mode (abstract). (to reach the fiber coupling location displaced from the overlap zone, CN’140’s taper culminates in a laterally shifted waveguide section that proceeds to the chip end face; this is inherently a “displacing” run from the taper tip to the endface.The geometry depicted and described (reverse overlap and lateral shift to the fiber mode region) is consistent with a straight slanted segment at a finite offset angle relative to the taper/center axis.)
Therefore it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Bian by substituting a straight slanted displacement run as suggested by CN’140 for the generic overlap-reducing displacement of Bian because it is a predictable design choice to realize a compact, well-controlled transition that positions the waveguide end where needed (e.g., to route, clear keep-outs, or reduce residual coupling). Further, the selection of a slant angle (range of 0.5° to 20°) is an obvious optimization to balance adiabaticity and length, yielding predictable results (KSR; In re Aller);.
As to claim 14, Bian discloses interlayer vertical coupling, cladding, tapered sections, gradual overlap change as well as minimizing loss/back-reflection/crosstalk via mode matching and controlled overlap (paras. [0014], [0017]-[0019]. [0039]-[0043], [0056]; Figs. 1A-1E, 2, 3), Bian doesn’t explicitly disclose wherein the first lateral offset distance is sufficiently large such that one or more effective indices of one or more waveguide modes of the second waveguide layer have a negligible change as the one or more waveguide modes cross a boundary between the first tip section and the second lateral interface.
CN’140 teaches “reversely overlapped” tapered waveguides and that the second waveguide has a side “far away from the second tapered waveguide” matched to the external fiber mode (abstract); (After coupling, the second waveguide proceeds in a region laterally displaced from the overlap zone, ensuring the fiber/mode region is unperturbed by the first waveguide, i.e., the effective index of modes in the second path remains essentially unchanged where the first taper ends),
Both Bian and CN’140 minimize insertion loss and reflections through adiabatic
coupling and by isolating non-overlapped regions from perturbations. A POSITA would adopt CN’140’s teaching of providing sufficient lateral separation (“far away”) after the taper to ensure the other path’s modal indices are not measurably perturbed at the transition boundary, directly addressing “negligible change” condition.
Therefore, it would have been obvious to one of ordinary skill in the art
before the effective filing date of the claimed invention to modify Bian wherein the first lateral offset distance is sufficiently large such that one or more effective indices of one or more waveguide modes of the second waveguide layer have a negligible change as the one or more waveguide modes cross a boundary between the first tip section and the second lateral interface because increasing offset distance beyond the evanescent coupling decay length is a routine design choice yielding predictable result of negligible mode-index perturbation-i.e., a result effective variable optimized by simulation.
As to claim 17, Bian doesn’t explicitly disclose wherein the first center axis and the second center axis are laterally offset by a second lateral offset distance in a first lateral direction that is parallel to the second lateral axis.
CN ’140 describes “reversely overlapped” first/second tapered waveguides, and that “one side of the second waveguide far away from the second tapered waveguide is matched with the mode of the external optical fiber” (Abstract; Description). (The “far away” fiber-matching region implies that the second waveguide’s centerline is laterally displaced from the overlap zone and, accordingly, from the first waveguide’s centerline in the coupling region. This teaches a configuration where the two waveguide center axes are intentionally laterally offset by a designed distance in the transverse direction).
Both references target low-loss coupling with controlled overlap and mode matching. Introducing a designed lateral center-axis offset between the first and second waveguides in US ’706 provides an additional degree of freedom to (i) tune coupling strength and adiabaticity, (ii) suppress back-reflection, and (iii) meet downstream placement constraints (keep-outs, crossings, fiber ports), as exemplified by CN ’140’s laterally displaced, fiber-matching geometry.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to select a transverse centerline offset because it is a routine, result-effective variable in directional/tapered couplers; it predictably adjusts coupling coefficient and residual crosstalk without changing the fundamental mechanism. A person of ordinary skill would apply CN ’140’s teaching to Bian to obtain the expected benefits.
As to claim 18, Bian doesn’t explicitly disclose wherein the second tip section is not spatially overlapped with the first constant width section.
CN ’140’s “reverse overlap” and the second waveguide’s side “far away” from the taper matched to the external fiber mode (Abstract; Description) imply that after completing the taper, the downstream segment (including any tip region at that end) is positioned laterally away from the overlap region. In such a layout, the second taper tip is not vertically overlapped with the constant-width section of the other waveguide because the centerlines are offset and the downstream path is deliberately routed “far away.” The teaching supports a geometry where the second waveguide’s tapered tip is laterally displaced such that it no longer vertically overlaps the first waveguide’s main body.
Avoiding vertical overlap between the second taper tip and the first main body helps (i) mitigate residual coupling/crosstalk after the intended coupling region, (ii) reduce back-reflections at transitions, and (iii) place the output waveguide where needed for subsequent interfaces—goals directly aligned with both references’ focus on low-loss, low-reflection transfers. CN ’140 expressly motivates moving the downstream waveguide section “far away” from the overlap region to match external modes (fiber), which inherently eliminates undesired vertical overlap with the other path’s main body.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to ensure no vertical overlap between the downstream taper tip and the other waveguide’s main body. This is a routine layout choice once lateral center-axis offset is introduced; it predictably suppresses unintended coupling outside the designed overlap region. A POSITA would make this modification to Bian in view of CN ’140 to achieve those expected benefits.
As to claim 19, Bian discloses the interlayer transition coupling structure of claim 17, wherein the first lateral offset distance extends from the first center axis in a second lateral direction that is parallel to the second lateral axis, and wherein the first lateral direction and the second lateral direction are opposite directions (Fig. 1A; the mini-waveguide is displaced upward in one direction, downward in the opposite).
As to claim 20, even though Bian teaches the first and second waveguides located in different layers/heights (e.g., “first height” and “second height” para. [0018]), Bian doesn’t explicitly disclose wherein the first waveguide layer and the second waveguide layer are part of a same waveguide layer having different thicknesses.
CN ‘140 implements coupling in a thin-film lithium niobate (TFLN) stack with a “first waveguide core layer” (thin-film LN) and a “second waveguide core layer” that is either a higher-index material than the insulating layer or a material with periodic high/low refractive index (Abstract; Description). Thus, CN ’140 teaches that coupling efficacy can be engineered through vertical modal confinement control in a single thin-film system by manipulating core thickness/index distribution (e.g., rib vs. slab thickness, periodic index patterning). While CN ’140 names separate “layers,” its disclosure that the second “layer” can be a periodic index region within the same thin-film platform suggests using intra-layer thickness/index engineering to realize distinct guided paths).
A POSITA seeking to simplify fabrication or reduce interlayer alignment tolerances in Bian’s interlayer coupler would recognize that two “effective layers” can be realized within a single deposited core film by patterning different thicknesses (rib/channel or step-height regions) or periodic index regions—techniques explicitly suggested by CN ’140’s thin-film and periodic index disclosures—to achieve similar vertical modal separation and coupling behavior. This reduces deposition/planarization steps and alignment complexity while preserving the evanescent-coupling mechanism and mode-matching strategy of US ’706.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that Implementing two effective waveguide “layers” as different thickness regions of the same core film is a well-understood substitute for stacking separate cores (result-effective variable) yields the predictable outcome of different effective indices/heights for controlled vertical coupling, consistent with the teachings/goals of both references (low-loss, adiabatic transfer).
As to claim 21, Bian doesn’t explicitly disclose wherein the first optical signal and the second optical signal are a same optical signal.
CN ’140 is a spot-size converter/end-face coupler designed to hand off the same optical signal between different guided structures (e.g., on-chip waveguide to external fiber, and vice versa) using reversed-overlap tapers to minimize insertion loss (Abstract; Description; The explicit purpose is transferring the same optical signal across a coupling interface with low loss and low reflection).
Both references are directed to low-loss, adiabatic transfer of light between guided structures. In the context of an interlayer coupler, a POSITA would intend to hand off the same optical signal (same data/wavelength/mode) between paths, as in CN ’140’s SSC, to avoid signal discontinuities and additional conversion steps.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to configure the interlayer coupler of Bian to transfer the same optical signal between the two paths. This is an obvious implementation of the shared goal (low-loss handoff of the same propagating wave). This is a routine, intended use and yields no unexpected result-merely the expected continuous transfer of the same mode/payload across the coupler.
As to claim 28, while Bian teaches tapered end portions on the second waveguide (e.g., toward a lateral interface at the coupling region, and optionally at the opposite end) Bia doesn’t explicitly disclose a third tapered section that tapers lengthwise, along the second center axis, from the second constant width section away from the first lateral interface and away from the second lateral interface.
CN’140 discloses two tapered waveguides that are “reversely overlapped” and states that “one side of the second waveguide far away from the second tapered waveguide is matched with the mode of the external optical fiber” (abstract). Thus beyond the coupling/overlap taper on the second waveguide includes a further geometry (a downstream taper/spot-size converter) on the side “far away” from the overlap region to shape the mode for a different environment (e.g., fiber). Functionally that additional taper originates from a constant-width section and proceeds in the non-coupling direction, i.e., away from the coupling endface and away from the opposite endface, consistent with placing an additional taper section along the second center axis beyond the constant-width section.)
Both Bian and C’140 aim to minimize insertion loss and back reflections by tailoring modal size/index matching using tapered sections. POSITA would recognize the benefit of further tapering the second waveguide downstream (away from the coupling end) to tailor the mode for subsequent routing, transitions, or external interfacing, exactly as taught by CN’1401’s “far away” fiber-matching taper. This improves system-level performance without altering the fundamental coupling mechanism at the interlayer region.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that adding a downstream (third taper) to the second waveguide from its constant-width section in the non-coupling direction is a routine, result-effective design step that yields predictable improvements in mode size, confinement, and interface loss for the next component. Placement/orientation along the second center axis is a straightforward layout choice governed by available length and target mode size.
Claim(s) 30 and 31 are is/are rejected under 35 U.S.C. 103 as being unpatentable over unpatentable over Bian in view of CN 115793140A (hereinafter CN’140) (translation provided) or Bian in view of Nesic and further in view of CN’140.
As to claim 30, Bian discloses an interlayer transition coupling structure, comprising:
a first waveguide mode path configured to propagate a first waveguide mode (first waveguide core 110 configured for optical signal propagation; paras. [0017]-[0019]; Fig. 1B (110 with main body 112 and end portion 111); and
a second waveguide mode path configured to propagate a second waveguide mode (second waveguide core 120 configured for optical signal propagation; paras. [0018]-[0019]; Fig. 1B (120 with main body and end portion 121),
wherein the first waveguide mode path and the second waveguide mode path are partially overlapped and are configured to couple the first waveguide mode and second waveguide mode (vertical overlap and coupling; first end portion 111 overlaid by second end portion 121 with a coupler including additional waveguide core(s) 150 between them; optical signal pass between cores with mode matching; paras. [0014], [0019], [0021], [0043]; Figs. 1A-1E),
wherein the first waveguide mode path has a first tip section and a constant-width portion (Bian teaches a coupling region including tapered portions and additional waveguide core(s) that are vertically stacked and laterally arranged to transfer optical signals. See ¶¶ [0019], [0037]-[0044]. (tapered end portion of first waveguide to a minimum width (Paras. [0039]-[0041])
wherein the first waveguide mode path has a displacement mode path starting at the waveguide tip section, wherein the displacement mode path is continuously displaced from the second waveguide mode path (continuous change in overlap along the longitudinal direction to achieve coupling/decoupling; [0043] (‘shapes …configured .. so that optical signal pass …” and that overlap and mode matching occur along the taper overlap; multiple embodiments show geometries where overlap between cores and/or intermediate mini-cores decreases along the length (e.g., Figs. 1-3)),
wherein the displacement mode path is configured to adiabatically decouple the first waveguide mode from the second waveguide mode or gradually couple the first waveguide mode to the second waveguide mode (adiabatically coupling/decoupling by tapering and/or by varying overlap along the length for mode matching; pars. [0014], [0043], [0056] (low-loss transmission, mode matching, evanescent coupling);
wherein the second waveguide mode path has a second tip section ((para. [0039]-[0041]; “width of the second end portion 121…tapers down ..essentially linearly.”).
Bian does not explicitly disclose the limitation such as, “wherein the second tip section is not spatially overlapped with the first constant width section”.
However, Bian teaches that the waveguide shapes and overlap geometry are selected to achieve mode matching and reduce signal loss, and that the geometry may vary depending on the separation distance and desired coupling behavior. See ¶¶ [0013], [0019], [0037]-[0044], [0056].
Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to arrange the tapered tip section of the second waveguide core so that it is not spatially overlapped with the constant-width section of the first waveguide core as a predictable design variation to control coupling geometry, manage mode matching, and reduce unwanted interaction between non-coupling portions of the waveguides. Under KSR v. Teleflex, 550 U.S. 398 (2007), a claim is unpatentable when it is directed to a predictable variation of known elements yielding no more than the expected results. The claimed non-overlap condition is such a predictable geometric adjustment in the context of Bian’s disclosed interlayer coupling structure.
Further, Nesic teaches waveguide regions that initially overlap or are close together and then become spatially disjoint after gradual divergence. See ¶¶ [0088]-[0093], [0099]-[0101].
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Bian’s interlayer waveguide coupling geometry in view of Nesic to provide a second tip section that is not spatially overlapped with the constant-width portion of the first waveguide mode path, as a predictable variation to achieve controlled adiabatic coupling/decoupling and low-loss signal transfer.
Under KSR v. Teleflex, 550 U.S. 398 (2007), combining familiar elements according to known methods to yield predictable results is obvious. The claimed non-overlapping tip arrangement and gradual displacement path would have been a predictable design variation in view of the combined teachings.
While Bain teaches continuous reduction of overlap, Bian doesn’t explicitly disclose a “displacement mode path starting at the waveguide tip section”.
CN ‘140 discloses two tapered waveguides that are “reversely overlapped” and notes that “one side of the second waveguide far away from the second tapered waveguide is matched with the mode of the external optical fiber (abstract). This geometry implies: (i) after the taper overlap, the waveguide continues along a laterally displaced run “far away” from the overlapped region to the endface; (ii) the displacement begins at the taper tip and increases (i.e., “continuously displaced”) to move the guided mode to a region sufficiently separated for the desired mode adaptation (spot-size converter). Thus CN’140 explicitly teaches a post-taper displacement path beginning at the tip, laterally moving the guided mode away from the other path/overlap zone).
Both Bian and CN’140 aim to minimize insertion loss and reflections through adiabatic coupling and controlled spatial overlap. Introducing an explicit displacement segment that begins at the taper tip and steadily increases spatial separation from the other path is a known approach to suppress residual coupling and reflections, and to route to subsequent interfaces (i.e., fiber ports, waveguide tracks).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that adding a displacement path beginning at the taper to as suggested by CN’140 to the interlayer coupling structure of Bian yields the predictable benefit of controlled decoupling and placement of the output waveguide away from the coupling region, with tradeoffs (length vs. loss) readily optimized via simulation. This is a routine, result-effective modification consistent with Bian and CN’1410’s teachings.
As to claim 31, Bian teaches tapered and displaced waveguide coupling structures where the lateral positioning and overlap of waveguide portions can be varied depending on coupling requirements and signal loss constraints. See ¶¶ [0019], [0037]-[0044].
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to make the second lateral offset distance greater than the first lateral offset distance in order to adjust the coupling geometry, increase the displacement between waveguide portions, and control the mode-matching region within the coupler. Such variation would have been a routine and predictable design choice in view of Bian’s disclosure of tapering, stacked coupling cores, and geometry-dependent coupling behavior.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). 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.
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/TARIFUR R CHOWDHURY/Supervisory Patent Examiner, Art Unit 2877
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