The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
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 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.
DETAILED ACTION
Applicant’s remarks filed 4/6/26 are acknowledged. No claims are amended. Claims 1 – 24 are pending.
Response to Amendments / Arguments
Applicant’s arguments regarding the amended claims versus the previously raised claim rejections under 35 USC 103 based on the Liu – Anderson – Sun combination have been fully considered but they are not persuasive, as detailed below.
(a) Applicant asserts that “Liu's device relies on region-specific structures and coupling behavior, rather than a single, continuous grating configuration performing all functions across the entire device” (p. 1 of the Remarks).
The Examiner notes the following:
(i) Applicant uses loose/general terms as “region-specific structures and coupling behavior” and “all functions” whose meanings is not defined by the preceding portion of the Remarks.
(ii) Applicant points out the alleged deficiencies of the Liu reference in a piece-meal fashion, instead of addressing the entire Liu – Anderson – Sun combination applied to claim 1. According to the teachings of Sun, the grating section would extend end-to-end so that the contra-directional coupler of the Liu – Anderson – Sun combination has “a single, continuous grating configuration performing all functions across the entire device”, however loosely stated by Applicant.
(b) Applicant makes a drawn-out argument (pp. 2 – 3) that attempts to prove that “the fundamental differences in operating principles and functional requirements between the device of Sun and the contra-directional coupler filter of Liu” (1st para. on p. 2)
The Examiner respectfully disagrees and notes the following:
(i) Contrary to Applicant’s assertion, there is no fundamental difference in the operating principles in Liu and Sun. Each reference discloses a spectral filter based on a 2x2 directional coupler with a grating comprised in one (straight) of a pair of waveguides making up the directional coupler, i.e., a grating-assisted directional coupler. The fundamental principle of operation is the same in both references: wavelength-selective coupling and reflection in a grating-assisted directional coupler. The same fundamental principle of operation also governs a grating-assisted directional coupler disclosed by the instant application and defined by claim 1.
(ii) What Applicant actually argues and calls “functional requirements” is a need for a proper (re)optimization of parameters (e.g., waveguide widths, shapes of waveguide bends, etc.) defining the grating-assisted directional coupler in Liu when the grating in the lower waveguide is extended end-to-end, according to Sun. As evidenced by paragraph bridging pp. 2 - 3 and the following paragraph of the Remarks, Applicant points out that simply inserting the physical structure of the coupler in Sun into the coupler of Liu would change its splitting ratio(s) and reflection efficiency. In this regard, Applicant is reminded that it is the teachings of Sun (a grating-assisted waveguide spanning end-to-end) that are used to properly modify the structure of Liu. It certainly requires (re)optimization of the parameters defining the coupler. However, Applicant’s attempt (3rd complete para. on p. 3) to present such (re)optimization as being above ordinary skill in the art is without merit, at least because it completely disregards a high level of ordinary skill in the art of optical waveguide devices. Practitioners of such art (including the Examiner in his previous career track) hold advanced degrees and possess in-depth professional expertise. Not only are they fully capable of performing numerical modeling of waveguide structures and their (re)optimization (if needed), but they routinely/regularly perform such tasks as part of their responsibilities and job descriptions.
(iii) Applicant’s assertion that such (re)optimization would cause “a change in the basic principle under which its construction was designed to operate” (ibid) is flawed for the above reasons: the fundamental principle of operation of the coupler in Liu, after its parameters are (re)optimized to accommodate an end-to-end grating (according to Sun), remains the same/unchanged.
(iv) Here is a simple example demonstrating the untenability of Applicant’s position. If an intended wavelength of the reflected/drop port (denoted as l2 in annotated Fig. 1 of Liu provided below from claim 1) were changed (for example, for a communication wavelength of 1,300 nm to another communication wavelength of 1,550nm), the coupling in the input/output 2x2 couplers and the reflectivity of the grating would be quite different at the new wavelength (1,550 nm) and the coupler would not operate properly till its parameters are (re)optimized (from their value optimized for l2 = 1,300 nm). According to Applicant’s untenable position, a person of ordinary skill in the art would not be able to (re)optimize the coupler parameters (for l2 = 1,550 nm) to restore the intended operation only because “would require a reengineering of the coupling profile along the device, balancing of reflection and transmission characteristics and a redesign of taper regions to account for altered coupling conditions”, as alleged by Applicant (3rd complete para. on p. 3). Such allegation is squarely refuted by daily work of practitioners in the art (designers of optical waveguide circuits/devices).
(c) Applicant’s arguments drawn to Anderson (pp. 4 – 5) are based on the same alleged difference in “fundamental differences in operating principles” and complete disregard of the high level of skill in the by presenting fairly routine modifications of parameters as being non-trivial and above ordinary skill in the art. The arguments are not persuasive at least for the reasons provided above for items (a) and (b).
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 of this title, 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 set forth in Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), that are applied 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.
Claims 1 – 24 are rejected under 35 U.S.C. 103 as being unpatentable over “Silicon photonic bandpass filter based on apodized subwavelength grating with high suppression ratio and short coupling length” by Liu et al, OPTICS EXPRESS, vol. 25, No. 10, pp. 11359 – 11364, 2017 (hereinafter Liu) in view of Anderson et al (US 2015/0104130 A1), and further in view of Sun et al (CN 112379485 A).
Regarding claim 1, Liu describes (Fig. 1; Abstract; Section 2) a contra-directional coupler (contra-DC) filter (“A compact silicon bandpass filter with high sidelobe suppression is proposed … our proposed apodized-SWG-based contradirectional coupler (contra-DC) in the Abstract) disposed on a (silicon) substrate (shown in Fig. 1), the contra-DC filter comprising (see annotated Fig. 1 below):
a bus waveguide (the upper solid waveguide in Fig. 1) having a first core; and
a grating element that includes a grating waveguide (the lower waveguide with a grating/segmented portion) having a second core (with tapered portions in the left and right tapers) and a first plurality of teeth (sub-wavelength grating (SWG)) that is optically coupled with the grating waveguide;
wherein the bus waveguide and grating element are configured to define first (left) and second (right) taper regions and a mirror region (central region on length Lc) located between the first and second taper regions, the mirror region being a strongly coupled region (due to a small(er) inter-waveguide gap) for a first light signal (denoted as l1,l2 in annotated Fig. 1 and being a CWDM wavelength channel in the near infra-red wavelength region around 1,550 nm (Abstract; para. bridging pp. 11360 – 11361; 1st para. of Section 4), the grating waveguide being included in each of the first and second taper regions and the mirror region;
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wherein the first taper region includes a first directional (2x2) coupler for transitioning the first light signal (l1,l2) between a first weak coupling region (with a wider inter-waveguide gap) and the mirror region; and wherein the second taper region includes a second directional (2x2) coupler for transitioning a second (thru/output) light signal (l2) between the mirror region and a second weak coupling region (with a wider inter-waveguide gap), the second (thru/output) light signal including at least a first (passed through) portion (l1) of the first light signal (l1,l2) (the wavelength l2 is mirrored/reflected into the drop channel, as illustrated in annotated Fig. 1).
Annotated Fig. 1 of Liu.
Liu states, by way of example but not limitation, that the first and second cores can be formed of silicon, but does not list (i) silicon nitride as another suitable/workable material choice. Liu does not teach that (ii) the first and second directional couplers can be configured as adiabatic directional couplers. Liu also does not teach that (iii) the grating waveguide (SWG) can extend along the entire length of the grating element. However, Anderson provides features (i) and (ii), as detailed below, and Sun discloses feature (iii).
As for feature (i), Anderson discloses a 2x2 directional coupler 100 (Figs. 1, 2, and 4; Abstract; para. 0018, 0019, 0021 – 0031, and 0033) comprising a pair of optically (evanescently) coupled waveguide cores 102,106. Anderson expressly states that that the two waveguide cores 102,106 can be formed of silicon (as in Liu) or silicon nitride (para. 0019).
It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention that the entire waveguide structure in Liu, including the tow waveguide cores and the teeth can be formed of silicon nitride as another suitable/workable material choice that is listed by Anderson and has lower optical loss compared to silicon (because silicon nitride is a dielectric material and does not have carrier-induced absorption in silicon). It is also noted that it has been held to be within the general skill of a worker in the art to select a known material on the basis of its suitability for the intended use as a matter of obvious design choice. See In re Leshin, 125 USPQ 416.
As for feature (ii), Anderson teaches that the disclosed directional coupler can be configured as an adiabatic directional coupler (Abstract; para. 001 and 0028 – 0030) by properly selecting the lengths and widths of its tapered portions (para. 0029 and 0030). It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention that the first and second directional couplers in Liu can be configured, in accordance with the teachings of Anderson, as adiabatic directional couplers. They have the benefits of low optical loss and (unintended) backreflection, a broad spectral bandwidth, and increased tolerance to fabrication deviations (“Because embodiments make use of adiabatic mode evolution and do not rely on physical symmetry along the device length, the devices can have very low loss, low back reflection, a large operating bandwidth, and a high degree of tolerance to fabrication variation” at para. 0018 of Anderson, emphasis added).
As for feature (iii), while Fig. 1 of Liu illustrates, by way of example but not limitation, a design wherein the second core does not extend continuously throughout the entire length of the grating waveguide, Sun discloses (Figs. 1, 4, and 6 – 10; Abstract; para. 0019 – 0034 and 0040 – 0046) a wavelength filter based on a 2x2 directional coupler that has essential structural similar to those in Liu and comprises:
a bus waveguide 101-103 having a first core that can be formed of silicon nitride (para. 0047); and
a grating element 104-107 (note that the length of segment 108 can be zero; para. 0021) that includes a grating waveguide having a second core (“a narrow waveguide” with a width tapered from 300 nm to 500 nm, as detailed at para. 0032) and a first plurality of teeth (extending laterally from the second core and having a width of 500 nm; para. 0032) that is optically coupled with the grating waveguide, the second core and the teeth of the first plurality thereof comprising silicon nitride (para. 0047), and wherein the grating element 104-107 has a first length and the grating waveguide extends along the entire first length (as seen in Fig. 1);
wherein the bus waveguide 101-103 and grating element 104-107 are configured to define first (left) and second (right) taper regions and a central region located between the first and second taper regions, the grating waveguide (comprising a distributed Bragg grating) being included in each of the first (left) and second (right) taper regions and the central region (as seen in Fig. 1); wherein the first (left) taper region includes a first directional (2x2) coupler for transitioning an input light signal between a first weak coupling region and the central region; and wherein the second (right) taper region includes a second directional (2x2) coupler for transitioning a coupled light signal between the central region and a second weak coupling region, the coupled light signal including at least a portion of the input light signal (as shown in Fig. 4).
It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention that the grating element in Liu can be modified so that the core of the grating waveguide (continuously) extends along the entire length of the grating element, as a suitable/workable design choice that is illustrated by Sun and can extend the free-spectral range of the filter so that “more independent wavelength channels can be supported and the channels do not interfere with each other” (para. 0002 of Sub). It aligns with and/or furthers the goal of Liu to suppress crosstalk/interference among CDWM wavelength channels (Abstract).
In light of the foregoing analysis, the Liu – Anderson – Sun combination teaches expressly or renders obvious all of the recited limitations.
As an aside and relevant comment to all claims, it is also noted that the contra DC filter of the Liu – Anderson – Sun combination has essential structural features (a contra-directional coupler comprising two adiabatic 2x2 directional couplers (according to Anderson) and one segmented waveguide (according to Liu and Sun), the waveguides having tapered portions (according to Anderson and Sun)) and a principle of operation (reflection of a certain wavelength(s) in the drop port, while passing others to a through port) that are substantially similar/identical to those of the contra-DC of the instant application, as evident from a direct side-by-side comparison of Fig. 1 of Liu and Fig. 1 of Sun (with a modification of tapered adiabatic couplers applied) versus Fig. 1 of the instant application.
Regarding claim 11, the teachings of Liu, Anderson, and Sun combine (see the arguments and motivation for combining, as provided above for claim 1) to teach expressly or render obvious all of the recited limitations, as detailed above for claim 1. Specifically, the Liu – Anderson – Sun combination considers a contra-directional coupler (contra-DC) filter disposed on a substrate (according to Liu), the contra-DC filter comprising (see annotated Fig. 1 of Liu provided above for claim 1):
a bus waveguide having a first core, the bus waveguide including (a) an input port for receiving a first light signal comprising a first plurality of wavelength signals (l1,l2 within a given CDWM wavelength channel; Fig. 4 of Liu) and (b) an output (thru) port for providing a second light signal that includes at least one wavelength signal (l1) of the first plurality thereof; and
a grating element comprising a first plurality of teeth and a grating waveguide having a second core, wherein the grating waveguide includes a drop port for providing a third light signal (l2) that includes at least one wavelength signal of the first plurality (l1,l2) thereof, and
wherein the grating element has a first length and the grating waveguide extends along the entire first length (according to Sun);
wherein each of the first and second cores and the teeth of the first plurality thereof comprises silicon nitride (according to Anderson and Sun); and
wherein the bus waveguide and grating element are arranged such that, for the first plurality of wavelength signals, they define:
(i) a strongly coupled region, the strongly coupled region defining a mirror region that includes a first portion of the bus waveguide and a first portion of the grating element, wherein the mirror region is configured to redirect the third light signal to the drop port (according to Liu);
(ii) a first (left) taper region configured to adiabatically transition (according to a combination of Liu and Anderson) between the strongly coupled region and a first weakly coupled region that is outside a footprint of the contra-DC filter (the leftmost portions of the first and second core can be extended well beyond the 1st taper region, as needed for a particular layout); and
(iii) a second (right) taper region configured to adiabatically transition (according to a combination of Liu and Anderson) between the strongly coupled region and a second weakly coupled region that is outside the footprint (the rightmost portions of the first and second core can be extended well beyond the 1st taper region, as needed for a particular layout).
Regarding claim 18, the teachings of Liu, Anderson, and Sun combine (see the arguments and motivation for combining, as provided above for claim 1) to teach expressly or render obvious all of the recited step limitations of a corresponding method of using the contemplated contra-DC filter, as detailed above for claim 1.
Regarding claim 2, the Liu – Anderson – Sun combination considers that the grating waveguide includes a drop port (see annotated Fig. 1 of Liu provided above for claim 1), and wherein the mirror region is configured to redirect a third light signal (l2) to the drop port, the third light signal (l2) including at least a second portion of the first light signal (l1,l2).
Regarding claims 3 – 5, 13 – 15, and 20 – 22, the Liu – Anderson – Sun combination renders obvious that, depending on a particular application, the third (dropped) light signal can include either a single wavelength signal or a CWDM wavelength channel that comprises a plurality of wavelength signals (within a ~ 20 nm spectral channel, as shown in Figs 2 and 4 of Liu and detailed by Liu in Section 3), wherein the wavelength channel is a CDWM wavelength channel (Abstract and Section 1 of Liu).
The Examiner took official notice in the Office Action of 1/13/26 that both the standard CDWM ITU grid and the standard DWDM ITU grid were well known in the art. Since Applicant has not traversed the official notice, the fact of common knowledge has become applicant admitted prior art. It would be obvious to a person of ordinary skill in the art that the CDWM wavelength channel in Liu can be aligned with the standard CDWM ITU grid and the plurality of wavelength signals aligned with the standard DWDM ITU grid in order to ensure inter-operability of telecommunication equipment by different developers/manufacturers.
Regarding claim 6, the Liu – Anderson – Sun combination considers that the first core, the second core, and the teeth of the first plurality thereof can consist of silicon nitride (as a suitable/workable material choice considered by Anderson and Sun).
Regarding claims 7, 16, and 23, the Liu – Anderson – Sun combination considers (Fig. 1 of Sun) that the first plurality of teeth includes a first series of teeth and a second series of teeth, each tooth of the first and second series of teeth having a width that depends on its position within its respective series (due to a longitudinally tapered second core; para. 0032 of Sun), wherein the first taper region includes the first series of teeth and the second taper region includes the second series of teeth.
Regarding claims 8, 17, and 24, the Liu – Anderson – Sun combination considers, by way of examples but not limitation, a range of suitable/wavelengths in the near infrared range: Liu considers a range around 1550 nm (Section 4) and Sun graphs (Fig. 3) performance within a range from 1400 – 1620 nm. It would be obvious to a person of ordinary skill in the art that the filter of the Liu – Anderson – Sun combination can be (re)optimized for operation at other wavelengths, such as within 1260 – 1360 nm, as intended by a particular application.
It is also noted that (i) the range limits depend on a particular application; that (ii) the instant application does not provide any criticality for the exact values of the recited range limits; that (iii) it has been held that discovering the optimum or workable ranges of prior art involves only routine skill in the art (In re Aller, 105 USPQ 233); and that (iv) it has been held that "A recognition in the prior art that a property is affected by the variable is sufficient to find the variable result-effective." In re Applied Materials', Inc., 692 F.3d 1289, 1297 (Fed. Cir. 2012). It is well settled that it would have been obvious for an artisan with ordinary skill to develop workable or even optimum ranges for result-effective parameters. In re Boesch, 617 F.2d 272, 276 (CCPA 1980); see also In re Woodruff, 919 F.2d 1575, 1577-78 (Fed. Cir. 1990). The Liu – Anderson – Sun combination intends the contemplated filter to operate at a particular wavelength of operation and, as such, regards it as a result-effective parameter.
Regarding claim 9, the Liu (Fig. 1) and Sun (Fig. 1) use segmented waveguides as distributed Bragg gratings/reflectors, the latter being a bandgap structure and a particular type of photonic crystal. Furthermore, Fig. 5 of Sun illustrates an embodiment comprising a photonic crystal structure defined by a plurality of holes (para. 0038). Such structure meets the most common definition of a photonic crystal.
Regarding claim 10, the Liu – Anderson – Sun combination considers a down-taper in the bus waveguide prior to the strongly coupled region (according to Figs. 2 and 3 of Anderson) in which case the first core has a first width at the input port and a second width at the mirror region, and wherein the first width is larger than the second width.
Regarding claims 12 and 19, the Liu – Anderson – Sun combination considers the first and second taper regions are configured (with apodized coupling strength) to mitigate the generation of sidelobes of the first light signal (“the high sidelobes can be effectively suppressed through apodization by tapering the coupling strength in the contra-DC with a Gaussian profile of the gap between the strip waveguide and the SWG waveguide” at last para. on Section 1 of Liu; “the sidelobes can be effectively suppressed by tapering the coupling strength, i.e., the coupling strength at the center of the coupling region is the strongest, while the coupling strength gradually reduces away from the center of the coupling region” at 1st para. of Section 2).
Conclusion
Applicant's arguments filed 4/6/26 have been fully considered but they are not persuasive and have failed to place the instant application in condition for allowance. 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 extension fee 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 date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to ROBERT TAVLYKAEV whose telephone number is (571)270-5634. The examiner can normally be reached 10:00 am - 6:00 pm, Monday - Friday.
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/ROBERT TAVLYKAEV/Primary Examiner, Art Unit 2896
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