DETAILED ACTION
This office action is in response to applicant’s amendment filed on June 26, 2026. Claims 1 and 12 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.
Claim 1 is rejected under 35 U.S.C. 103 as being unpatentable over Kawashima et al. (US 2013/0209111 A1, herein “Kawashima”) in view of Gerlach et al. (US 2003/0179972 A1, herein “Gerlach”).
Kawashima discloses an optical waveguide interferometer in Fig. 6A, comprising:
an input section (6DC1);
a middle section (6D1/6D2);
an output section (6DC2);
a first arm portion (6D2) having a first length that spans the input section, the middle section, and the output section; and
a second arm portion (6D1) having a second length that spans the input section, the middle section, and the output section;
wherein the first length of the first arm portion is less than the second length of the second arm portion; wherein the second arm portion has a curved shape;
wherein the first arm portion has a first bend at a transition of the first arm portion between the input section and the middle section;
wherein the second arm portion has a second bend at a transition of the second arm portion between the input section and the middle section;
wherein the first arm portion has a third bend at a transition of the first arm portion between the middle section and the output section;
wherein the second arm portion has a fourth bend at a transition of the second arm portion between the middle section and the output section;
wherein the first arm portion extends in a straight line to a third bend at a transition between the middle section (6D1/6D2) and the output section (6DC2);
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wherein the first angle (annotated as θ1) is defined by the first arm portion after the first bend at the transition of the first arm portion between the input section and the middle section and the second arm portion at the transition of the second arm portion between the input section and the middle section after the second bend;
wherein the second angle (annotated as θ2) is defined by the first arm portion before the third bend at the transition of the first arm portion between the middle section and the output section and the second arm portion before the fourth bend at the transition of the second arm portion between the middle section and the output section.
However, Kawashima does not explicitly teach the first angle and the second angle are equal and wherein the first angle and the second angle are in a range of about 5-70 degrees.
Gerlach teaches unequal arm Mach-Zehnder interferometric devices (10) as shown in Fig. 4 as a tunable filter in which the waveguide lengths of the filter’s elements are optimized for filter performance results (Para [0030]). The filter has fixed couplers (11) such that each coupler has a selected coupling angle θ. Each of the fixed couplers (11) thus would share the same coupling angle θ and phase shifters 12 form Na actuator, which can affect the phase and coupling of the interferometric device (10) (Para [0033]).
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It would have been obvious to one having ordinary skill at the time of filing to recognize the fixed coupling angle at the input and the output of the cascading interferometer of Gerlach can be modified to the coupler in Kawashima’s cascading interferometer. One would be motivated to employ fixed couplers to ensure stable, predictable light splitting, which eliminates the need for extra tuning control. Thus fixed couplers make the device simpler, cheaper, and less prone to errors.
However, Kawashima in view of Gerlach do not explicitly teach the first angle and second angle (theta) are in a range of about 5-70 degrees.
Gerlach teaches the coupling angle θ is given by
θ
=
2
π
∆
n
e
f
f
l
c
λ
wherein the angle theta, lengths variables delta, and actuator phase variable phi defines a filter response for light signals at frequency f. This method comprises selecting starting values for the variables, determining the optimized objective predetermined property of a desired filter response corresponding to the variables, and computationally varying the variables from the starting values to find values of the variables corresponding to the desired filter response (Para [0017]).
It would have been obvious to one of ordinary skill in the art at the effective filing date of the invention to computationally optimize the angle
θ
to find the desired filter response given the operating wavelength (band) 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 12 is rejected under 35 U.S.C. 103 as being unpatentable over Kawashima in view Gerlach as applied to claim 1 above, and further in view of Lipson et al. (US 2011/0102804 A1, herein “Lipson”).
Kawashima in view of Gerlach teach the invention of claim 1, but Kawashima in view of Gerlach do not teach a first span of the second arm portion in the middle section has a width that is different than a width of a second span of the second arm portion in the middle section.
Lipson teaches a passively thermally stabilized Mach-Zehnder interferometer (MZI 100) works on the principle that the guided mode have different effective mode index changes with temperature in the two arms of the MZI, induced by the different waveguide widths. The thermo-optic effect between the two interfering arms is balanced or adjusted while still maintaining a phase difference between the two arms as required by the filter specification (Para [0035]).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to recognize different the waveguide widths between the two interferometer arms would induce a difference in effective index of the waveguides, thus inducing a phase difference between the two arms. One would be motivated to induce a phase difference between the two arms in the MZI to design the MZI as an optical switch or optical modulator.
Response to Arguments
Applicant's arguments filed June 26, 2026 have been fully considered but they are not persuasive.
Applicant argues the newly amended limitations to claim 1 overcame the prior arts of record.
The examiner disagrees. Claim 1 recites the combined limitations of claims 1-5 and further added “the first angle and the second angle are in a range of about 5-70 degrees.” The rejection above addressed each and every limitations of claim 1 over the prior arts to Kawashima in view of Gerlach, including the angle is in a range of about 5- 70 degrees.
Applicant further argues the obviousness rejection under 35 U.S.C. § 103 is inconsistent with the Restriction Requirement (mailed 1/15/2026) because the restriction set forth the restricted species and sub-species as independent and distinct. Thus, an obviousness rejection that “relies on combining references based on subject matter that bears no difference with regard to the rationale of the Restriction Requirement” is inconsistent.
The examiner respectfully disagrees. The restriction requirement determined the species or sub-species to be non-obvious variants of each other, not whether the elected species or sub-species are not obvious over the prior arts. The obviousness rejection is determined to be obvious over the prior arts of Kawashima in view of Gerlach. The rejection did not find the elected species or sub-species obvious of among the restricted species or sub-species.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. PTO-892:A-D.
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.
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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