DETAILED ACTION
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 .
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(s) 1-4, 6, and 8-16, and 18-19 are rejected under 35 U.S.C. 103 as being unpatentable over Chen et al. (US 20090310627 A1) in view of Castro et al. (US 20180259422 A1).
Regarding Claim 1, Chen teaches a chromatic dispersion measurement method for characterizing an optical fiber link under test from a proximal end using an OTDR/CD-OTDR arrangement (Chen: [0024], [0076]-[0080]). In particular, Chen teaches a single-end CD-OTDR that measures chromatic dispersion by measuring the relative time-of-flight propagation for short optical pulses at different wavelengths reflected from a reflector at the distal end of the fiber under test. Chen further teaches tuning the pulsed laser to a number of discrete wavelengths within a desired range, e.g., 146-1630nm,v and processing the resulting signals to obtain a measure of chromatic dispersion (Chen: [0076]-[0078]). Chen therefore teaches performing OTDR acquisition toward an optical fiber link under test from a proximal end; using mutually different wavelengths for the test signal by performing a set of acquisitions at corresponding wavelengths; and calculating chromatic dispersion from values associated with returned signals at those different wavelengths.
However, Chen does not expressly teach that each OTDR acquisition uses a plurality of light pulses in accordance with a known sequence of pulses, nor does Chen expressly teach extracting the remote reflective peak position by calculating a cross-correlation between the known sequence and acquired trace.
Castro teaches those missing features. Castro discloses a correlation optical time-domain reflectometer (C-OTDR) in which transmitted light is modulated with a known pulse/code sequence and launched into one end of the fiber under test, the corresponding returned/backscattered signal is acquired as a trace, and the received signal is correlated with the transmitted known sequence to identify the temporal position of reflection events (Castro: [0015]-[0018], [0044)-[0048], [0053]-[0059]). Castro explicitly states that the reflected signal is correlated with the transmitted sequence and that the resulting correlation peaks indicated the temporal position, and therefore the distance of reflection events (Castro: [0015], [0048]). Cast5o further teaches multi-wavelength embodiments using transmitter at different wavelength (Castro: [0046], [0062]-[0071]).
It would have been obvious to one of ordinary skill in the art at the time of the invention to modify Chen’s chromatic-dispersion OTDR technique to employ the known coded-sequence / cross-correlation processing of Castro to extract the position of the remote end reflective peak for each wavelength. The motivation would have been to obtain Castro’s expressly taught benefits of improved range, sensitivity, resolution, and dynamic range in the OTDR context while still using Chen’s multi-wavelength time-of-flight approach to calculate chromatic dispersion. Such a modification merely applies a known OTDR signal-processing technique to a known OTDR-based chromatic-dispersion measurement system for its recognized benefit, yielding predictable results.
Regarding Claim 2, Chen further expressly teaches pe4rforming a set of OTDR acquisitions for a corresponding set of mutually different wavelengths, where the control unit tunes the pulsed laser to a number of discrete wavelengths (Chen: {0077}-[0078]).
Regarding claim 3, Chen teaches pulsing different-wavelength sources with a known timing relationship, including simultaneous pulsing or a known predetermined time difference (Chen: [0078]-[0080]). Castro also teaches transmitting multiple wavelength-coded signals using transmitters at different wavelengths and delay control (Castro: [0046], [0067]-[0071]).
Regarding Claim 4, Chen further teaches determining chromatic dispersion from wavelength-dependent propagation timing / relative group delay in a single-ended CD-OTDR arrangement (Chen: [0076]-[0078]).
Regarding Claim 6, Castro teaches that C-OTDR may operate with periodical sequence and that such sequences have useful autocorrelation properties (Castro: [0017]).
Regarding Claim 8, Castro further teaches a coded OTDR pulse sequence (Castro: [0015]-[0018], [0053]-[0059]).
Regarding Claim 9, Castro teaches correlating the received signal with the mathematical version of the transmitted sequence (Castro: [0048]). In the pulsed OTDR context, using the mathematical version of a transmitted pulse sequence reasonably reads on or renders obvious the use of an impulse pulse response of the known sequence for cross-correlation.
Regarding Claim 10, it is the system counterpart of claim 1 and is rejected for substantially the same reasons set forth above regarding claim 1.
Regarding Claim 11, Chen further teaches general multi-wavelength chromatic-dispersion measurement framework (Chen: [0076]).
Regarding Claim 13, Chen further expressly teaches a tunable pulsed laser arrangement for reflectometric and CD-OTDR use (Chen: Fig. 5, [0076]-[0080]).
Regarding Claim 14, Chen acknowledges that OTDRs employing several DFB lasers selectable individually to provide pulses at different discrete wavelengths were known (2018Chen: [0007]). It would have been obvious to substitute a known plurality of discrete wavelength laser sources for Chen’s tunable laser source as an obvious design alternative for generating test signals at multiple wavelengths, especially where only a discrete wavelength set is needed.
Regarding Claim 15, Chen teaches detector(s) for receiving reflected return light in the reflectometric apparatus (Chen: [0024], [0076]).
Regarding Claim 18, it is rejected for the same reasons set forth with respect to claim 8,
Regarding Claim 19, it is the system counterpart of claim 4 and it is rejected for the same reasons set forth with respect to claim 4
Claims 5 and 20 are rejected under 35 U.S.C. § 103 as being unpatentable over Chen et al. (US 2009/0310627 A1) in view of Castro et al. (US 2018025946 A1), and further in view of Page et al. (“Measuring chromatic dispersion of optical fiber using time-of-flight and a tunable multi-wavelength semiconductor fiber laser,” Optics Communications, Vol. 265, pp. 161-170 (2006), IDS).
Regarding Claims 5, the combination of Chen and Castro does not specifically disclose that the OTDR acquires at least three mutually different wavelengths; fits a function on group delay versus wavelength values; wherein the function corresponds to a Sellmeier model of delay as a function of wavelength; and calculating chromatic dispersion from the fitted function.
However, Page et al. teach determining chromatic dispersion from multiple wavelength-dependent time-of-flight/group-delay values and using that information to derive chromatic-dispersion characteristics of the fiber (entire reference). It would have been obvious to use at least three wavelengths and to fit the resulting group-delay-versus-wavelength data with a known dispersion model in order to reduce measurement noise and obtain a smooth chromatic-dispersion characterization across wavelength, since such curve fitting is a conventional data-analysis technique in optical fiber dispersion measurement.
It would have been obvious to apply the known group-delay/chromatic-dispersion analysis of Page et al. to the multi-wavelength reflectometric measurements of Chen, as improved by the coded-sequence correlation extraction of Castro et al., in order to obtain chromatic-dispersion values from wavelength-dependent reflected timing data.
Claim 20 is the system counterpart of claim 5 and is rejected for the same reasons.
Claims 7 and 17 are rejected under 35 U.S.C. § 103 as being unpatentable over Chen et al. (US 2009/0310627 A1) in view of Castro et al. (US 2018025946 A1), and further in view of Pimpinella et al. (US 20200174183 A1).
Regarding Claims 7 and 17, the combination of Chen and Castro does not expressly teach that the sequence of pulses comprises a chirped sequence of pulses. However, using chirped pulses is well known in the art, for example, Pimpinella teaches to uses chirped pulses for optical fiber text (Pimpinella: [0037]). It would have been obvious for an ordinary skilled person to the art to used chirped pulses in the system of Chen and Castro in order to accurately characterize signaling speed the fiber undertest is capable of supporting (Pimpinella: [0038]).
Response to Arguments
Applicant's arguments filed 7/17/2026 have been fully considered but they are not persuasive.
Claims 1-4, 6, and 8-16, and 18-19 are rejected under 35 U.S.C. 103 as being unpatentable over Chen et al. (US 20090310627 A1) in view of Castro et al. (US 20180259422 A1).
Applicant argues “that the Office Action fails to establish a prima facie case of obviousness” because the “rejection is not supported by a valid rationale”. However, in the rejection of claim 1, the Office Action clearly states: “It would have been obvious to one of ordinary skill in the art at the time of the invention to modify Chen’s chromatic-dispersion OTDR technique to employ the known coded-sequence / cross-correlation processing of Castro to extract the position of the remote end reflective peak for each wavelength. The motivation would have been to obtain Castro’s expressly taught benefits of improved range, sensitivity, resolution, and dynamic range in the OTDR context while still using Chen’s multi-wavelength time-of-flight approach to calculate chromatic dispersion. Such a modification merely applies a known OTDR signal-processing technique to a known OTDR-based chromatic-dispersion measurement system for its recognized benefit, yielding predictable results.”
The combination would be: take the CD-OTDR / multiwavelength reflective-end measurement of Chen et al. (US 20090310627 A1), substitute the OTDR pulse launch/detection technique with the coded/correlation OTDR of Castro et al. (US 20180259422 A1), thereby arriving at a system using known pulse sequences and correlation peak extraction for a remote-end reflective event at multiple wavelengths, then determine chromatic dispersion from the wavelength-dependent peak locations. It would have been obvious to one of ordinary skill in the art at the time of the invention to modify the CD-OTDR method of Chen et al. (US 20090310627 A1) to use the known pulse sequence and correlation processing of Castro et al. (US 20180259422 A1) in order to improve OTDR sensitivity and dynamic range while still measuring chromatic dispersion from the wavelength-dependent location of the reflective peak. That is a reasonable obviousness combination of the applied reference to come up with the claimed method. Therefore, the rejections of Claims 1-4, 6, and 8-16, and 18-19 still stand.
Claims 5 and 20 are rejected under 35 U.S.C. § 103 as being unpatentable over Chen et al. (US 2009/0310627 A1) in view of Castro et al. (US 2018025946 A1), and further in view of Page et al. (“Measuring chromatic dispersion of optical fiber using time-of-flight and a tunable multi-wavelength semiconductor fiber laser,” Optics Communications, Vol. 265, pp. 161-170 (2006), IDS)
Chen et al. (US 20090310627 A1) teach single-ended chromatic dispersion measurement using OTDR acquisitions at multiple wavelengths, detecting a reflective end-of-fiber event, and determining group delay and chromatic dispersion from wavelength-dependent time-of-flight measurements. Page et al. teach measuring chromatic dispersion of optical fiber using a time-of-flight approach with a tunable multi-wavelength semiconductor fiber laser, obtaining group delay as a function of wavelength, and deriving chromatic dispersion from the measured delay data. Castro et al. (US 20180259422 A1) teach OTDR methods using known pulse sequences and correlation processing to improve sensitivity, resolution, and dynamic range. It would have been obvious to one of ordinary skill in the art at the time the invention was made to modify the chromatic dispersion measurement technique of Chen et al. (US 20090310627 A1), as informed by Page et al., to use the coded/correlation OTDR acquisition and peak detection techniques of Castro et al. (US 20180259422 A1) in order to improve measurement sensitivity and dynamic range while preserving the known wavelength-dependent group-delay-based chromatic dispersion determination. Further, in view of Page et al., it would have been obvious to fit a function to group delay data obtained at multiple wavelengths, including a Sellmeier-type function, as an analytical technique for determining chromatic dispersion from the measured data. Accordingly, claims 5 and 20 would have been obvious over the combined teachings of the cited references.
Claims 7 and 17 are rejected under 35 U.S.C. § 103 as being unpatentable over Chen et al. (US 2009/0310627 A1) in view of Castro et al. (US 2018025946 A1), and further in view of Pimpinella et al. (US 20200174183 A1).
Chen et al. (US 20090310627 A1) teach a single-ended CD-OTDR method for measuring chromatic dispersion in an optical fiber link using OTDR acquisitions at multiple wavelengths, detecting a reflective end-of-fiber event, and determining chromatic dispersion from wavelength-dependent time-of-flight/group-delay measurements. Castro et al. (US 2018025946 A1) teach OTDR systems that employ known pulse sequences and correlation processing to improve sensitivity, resolution, and dynamic range, including periodic or coded pulse sequences and correlation-based peak detection. Pimpinella et al. (US 20200174183 A1) expressly teach that the electrical test signal driving the optical transmitter may comprise a pulse, pulse sequence, chirped pulses, or any combination of pulses, and further teaches cross-correlation-based processing of return signals for fiber length measurement. It would have been obvious to one of ordinary skill in the art at the time the invention was made to modify the CD-OTDR method of Chen et al. (US 20090310627 A1)to use the pulse-sequence/correlation OTDR techniques of Castro et al. (US 2018025946 A1) and further to employ a chirped sequence of pulses as taught by Pimpinella et al. (US 20200174183 A1), because such substitution would have predictably improved measurement robustness, sensitivity, and dynamic range while still allowing extraction of the remote reflective peak used in chromatic dispersion determination. Accordingly, claims 7 and 17 would have been obvious over the combined teachings of the cited references.
Conclusion
THIS ACTION IS MADE FINAL. Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
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/QUAN ZHEN WANG/Supervisory Patent Examiner, Art Unit 2685
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