The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
DETAILED ACTION
Claim Objections
Claims 7 and 9 are objected to because of the following informalities:
Claim 7 recites the limitation “the first and second output lights does not include” which has a typographical error. For the purposes of this Action, the limitation is interpreted as “the first and second output lights do not include”.
Claim 9 recites the limitation “A bias voltage adjustment method of optical modulator comprising” which appears to have a typesetting error/omission. For the purposes of this Action, the limitation is interpreted as “A bias voltage adjustment method of an optical modulator comprising”. Appropriate corrections are required.
Claim Rejections - 35 USC § 102
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.
Claim 9 is rejected under 35 U.S.C. 102(a)(2) as being anticipated by Katou et al (US 2017/0276973 A1).
Regarding claim 9, Katou discloses (Fig. 4; Abstract; para. 0009, 0021 – 0032, and 0070 – 0075) a bias voltage adjustment method of an optical modulator comprising (see annotated Fig. 4 below):
in a third (main) Mach-Zehnder type optical modulator MZM (para. 0032) in which a first (nested) Mach-Zehnder type optical modulator is provided on one (upper) of two arms and a second (nested) Mach-Zehnder type optical modulator is provided on the other (lower) of the two arms (“an optical modulation section formed as a nest-type optical waveguide in which two Mach-Zehnder type optical waveguides are disposed in a nest shape, and an optical modulation section in which two nest-type optical waveguides are additionally disposed in a nest shape” at para. 0059; also para. 0071);
monitoring (with the 1st PD) a first output light from the first Mach-Zehnder type optical modulator and outputting a first monitor signal (to a corresponding output electrical port 81(B)) indicating a monitoring result (para. 0072 and 0073);
monitoring (with the 2nd PD) a second output light from the second Mach-Zehnder type optical modulator and outputting a second monitor signal (to a corresponding output electrical port 81(B)) indicating a monitoring result (para. 0072 and 0073);
monitoring (with the 3rd PD) a third output light from the third Mach-Zehnder type optical modulator and outputting a third monitor signal indicating a monitoring result; and
independently adjusting first to third bias voltages provided to the first to third Mach-Zehnder type optical modulators based on the first to third monitor signals, respectively (“The optical modulation sections M(a) to M(d) perform optical modulation by using modulation signals different from each other, and are constituted to independently perform a bias control of the modulation signals” at para. 0028; “An intensity variation of light, which is output from the Mach-Zehnder type optical waveguide, shows, for example, sinusoidal function characteristics with respect to a voltage that is applied to a modulation electrode. It is necessary to set a modulation signal, which is applied to the modulation electrode, to an appropriate operation bias point so as to obtain an optimal intensity of output light in accordance with a usage of the optical modulator” at para.
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0005, emphasis added).
Annotated Fig. 4 of Katou.
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 – 3 and 5 – 8 are rejected under 35 U.S.C. 103 as being unpatentable over Katou in view of Doi et al (US 2003/0147591 A1).
Regarding claim 1, Katou discloses (Fig. 4; Abstract; para. 0009, 0021 – 0032, and 0070 – 0075) an optical modulator comprising (see annotated Fig. 4 provided above for claim 9):
a third (main) Mach-Zehnder type optical modulator MZM (para. 0032) in which a first (nested) Mach-Zehnder type optical modulator is provided on one (upper) of two arms and a second (nested) Mach-Zehnder type optical modulator is provided on the other (lower) of the two arms (“an optical modulation section formed as a nest-type optical waveguide in which two Mach-Zehnder type optical waveguides are disposed in a nest shape, and an optical modulation section in which two nest-type optical waveguides are additionally disposed in a nest shape” at para. 0059; also para. 0071);
a first photodetector (1st PD) configured to monitor a first output light from the first Mach-Zehnder type optical modulator and output a first monitor signal (to a corresponding output electrical port 81(B)) indicating a monitoring result (para. 0072 and 0073);
a second photodetector (2nd PD) configured to monitor a second output light from the second Mach-Zehnder type optical modulator and output a second monitor signal (to a corresponding output electrical port 81(B)) indicating a monitoring result (para. 0072 and 0073);
a third photodetector (3rd PD configured to monitor a third output light from the third Mach-Zehnder type optical modulator and output a third monitor signal (to a corresponding output electrical port 82(B)) indicating a monitoring result (para. 0072 and 0073).
Katou expressly teaches that first to third bias voltages can be independently adjusted and provided to the first to third Mach-Zehnder modulators (MZMs) based on the first to third monitor signals, respectively (“The optical modulation sections M(a) to M(d) perform optical modulation by using modulation signals different from each other, and are constituted to independently perform a bias control of the modulation signals” at para. 0028; “An intensity variation of light, which is output from the Mach-Zehnder type optical waveguide, shows, for example, sinusoidal function characteristics with respect to a voltage that is applied to a modulation electrode. It is necessary to set a modulation signal, which is applied to the modulation electrode, to an appropriate operation bias point so as to obtain an optimal intensity of output light in accordance with a usage of the optical modulator” at para. 0005).
While Katou does not explicitly illustrate a bias voltage generation unit configured to independently adjust the bias voltages and apply them to the Mach-Zehnder modulators, Doi discloses (Figs. 10 and 11; Abstract; para. 0109 – 0147) an optical modulator comprising at least two Mach-Zehnder modulators 21,41 (para. 0109), a first photodetector 37 configured to monitor a first output 23d from a first MZM 21, and a second photodetector 38 configured to monitor a second output 24d from a second MZM 41 (para. 0140 and 0141). Doi expressly teaches and explicitly illustrates a bias voltage generation unit 35,36 configured to independently adjust a first bias voltage (by the bias control section 35) to the first MZM 21 and a second bias voltage (by the bias control section 36) to the second MZM 41 (“Consequently, the feedback control of the bias voltage performed for compensating for a variation of the operating point voltage of the first optical modulator 21 and the feedback control of the bias voltage performed for compensating for a variation of the operating point voltage of the second optical modulator 41 are performed independently of each other” at para. 0146; also para. 0127 – 0129, 0141, 0145, and 0147).
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 optical modulator of Katou can comprise, as generally rendered obvious by Katou and explicitly illustrated by Doi, a bias voltage generation unit configured to independently adjust first to third bias voltages provided to the first to third Mach-Zehnder type optical modulators based on the first to third monitor signals, respectively, in order to enable proper operation (biasing) of all of the Mach-Zehnder modulators.
In light of the foregoing analysis, the Katou – Doi combination teaches expressly or renders obvious all of the recited limitations.
Regarding claim 8, the teachings of Katou and Doi 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 Katou – Doi combination considers an optical transmitter (“Such an optical modulator as just described is provided, for example, in an optical transmitter” at para. 0055 of Doi) comprising:
a light source (“input light from a light source (semiconductor laser) not shown is introduced to the first optical waveguide 23” at para. 0139 of Doi);
an optical modulator configured to modulate a light from the light source to output an optical signal; the optical modulator comprising (see annotated Fig. 4 of Katou provided above for claim 9):
a third (main) Mach-Zehnder type optical modulator MZM (para. 0032) in which a first (nested) Mach-Zehnder type optical modulator is provided on one (upper) of two arms and a second (nested) Mach-Zehnder type optical modulator is provided on the other (lower) of the two arms (“an optical modulation section formed as a nest-type optical waveguide in which two Mach-Zehnder type optical waveguides are disposed in a nest shape, and an optical modulation section in which two nest-type optical waveguides are additionally disposed in a nest shape” at para. 0059; also para. 0071);
a first photodetector (1st PD) configured to monitor a first output light from the first Mach-Zehnder type optical modulator and output a first monitor signal (to a corresponding output electrical port 81(B)) indicating a monitoring result (para. 0072 and 0073);
a second photodetector (2nd PD) configured to monitor a second output light from the second Mach-Zehnder type optical modulator and output a second monitor signal (to a corresponding output electrical port 81(B)) indicating a monitoring result (para. 0072 and 0073);
a third photodetector (3rd PD configured to monitor a third output light from the third Mach-Zehnder type optical modulator and output a third monitor signal (to a corresponding output electrical port 82(B)) indicating a monitoring result (para. 0072 and 0073); and
a bias voltage generation unit (generally rendered obvious by Katou and explicitly illustrated by Doi, e.g., Fig. 11) configured to independently adjust first to third bias voltages provided to the first to third Mach-Zehnder type optical modulators based on the first to third monitor signals, respectively.
Regarding claim 2, the Katou – Doi combination considers that the three bias voltages are adjusted independently from one another and renders obvious that the bias voltage generation unit can be configured to adjust the third bias voltage in the third (main) MZM after adjusting the first and second bias voltages in the first and second (nested) MZMs so that the optical power levels in the two arms of the third (main) MZM are set and stabilized before its bias point/phase is set.
Regarding claim 3, the Katou – Doi combination considers that the optical modulator and the photodetectors are configured as semiconductor devices formed on the same semiconductor substrate 1 (as shown in Figs. 1 – 4 of Katou; “Examples of the substrate 1 include a substrate such as quartz and a semiconductor in which an optical waveguide can be formed” at para. 0024; also para. 0071 and 0072).
Regarding claim 5, Katou teaches (Fig. 4) that the optical modulator further comprises:
first to third couplers (1x2 and 1x3 couplers) respectively provided at output ends of the first to third Mach- Zehnder type optical modulators, each of the first to third couplers having two inputs and at least two outputs (denoted as 21,22 in Fig. 1; para. 0032 – 0034),
wherein the first photodetector (1st PD) detects the first output light from one output of the first coupler,
the second photodetector (2nd PD) detects the second output light from one output of the second coupler,
the third photodetector (3rd PD) detects the third output light from one output of the third coupler,
the other output of the first coupler is connected to one input of the third coupler, and the other output of the second coupler is connected to the other input of the third coupler, and
an output light of the optical modulator is output from the other output of the third coupler.
As an aside and relevant comment, it is noted that Katou uses 2 x 2 couplers with one monitoring waveguides 22 which directly correspond to the monitoring waveguides WG12,WG23 in Fig. 3 of the instant application.
Regarding claim 6, Katou teaches (Fig. 4) that the first to third photodetectors (the 1st PD through the 3rd PD) respectively monitor the first to third Mach- Zehnder type optical modulators, and each of the first to third photodetectors does not output a signal including a monitoring result of another Mach-Zehnder type optical modulator. Such independent monitoring is also detailed in Fig. 1.
Regarding claim 7, Katou teaches (Fig. 4) that the first and second output lights does not include a (monitoring) signal that the third photodetector detects to adjust the first and second bias voltages provided to the first and second Mach- Zehnder type optical modulators after the first and second output lights are multiplexed and thereby converted into the third output light. Such independent monitoring by independent optical taps/couplers is also detailed in Fig. 1.
Claim 4 is rejected under 35 U.S.C. 103 as being unpatentable over Katou in view of Doi, and further in view of Hayashi et al (US 2013/0209021 A1).
Regarding claim 4, the Katou – Doi combination considers that the contemplated optical modulator and the photodetectors are configured as semiconductor devices formed on the same semiconductor substrate 1 (as shown in Figs. 1 – 4 of Katou; e.g., “Examples of the substrate 1 include a substrate such as quartz and a semiconductor in which an optical waveguide can be formed” at para. 0024; also para. 0071 and 0072) and receive input light from a light source (“input light from a light source (semiconductor laser) not shown is introduced to the first optical waveguide 23” at para. 0139 of Doi). While the Katou – Doi combination does not expressly teach that the light source can be integrated with the optical modulator and the photodetectors on the same semiconductor substrate, Hayashi discloses (Fig. 1; Abstract; para. 0045 – 0054) a light source 11 that outputs a light to a third (main) Mach-Zehnder type optical modulator and is configured as a semiconductor device and formed on the same substrate as the optical modulator 13 and monitoring photodetectors 20.
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 light source of the Katou – Doi combination can be integrated with the optical modulator and the photodetectors on the same semiconductor substrate, as a design choice that is expressly taught by Hayashi and reduces an overall device/transmitter size/footprint (para. 0072 of Hayashi).
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
US 2013/0209021 A1
US 2020/0278589 A1
US 2018/0031870 A1
US 2014/0307996 A1
US 8,909,006 B2
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/ROBERT TAVLYKAEV/Primary Examiner, Art Unit 2896