DETAILED ACTION
This office action is in response to applicant’s submission filed on February 2, 2026. Claim 3 was previously canceled. Claims 1-2 and 4-15 are pending and rejected.
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 .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on February 2, 2026 has been entered.
Information Disclosure Statement
The information disclosure statement (IDS) submitted on December 4, 2025 has been considered. The submission is in compliance with the provisions of 37 CFR 1.97. Accordingly, an initialed and dated copy of Applicant's IDS form 1449 is attached to the instant Office action.
Response to Amendment
This communication is in response to the amendment filed on February 2, 2026. The Examiner has acknowledged the amended claims 1, 5, 7-9, 12, and 13. Claim 3 was previously canceled. Claims 1-2 and 4-15 are pending and are rejected.
Response to Arguments
Applicant’s Arguments (Remarks) filed February 2, 2026 have been fully considered, but are not persuasive.
Applicant’s arguments with respect to claims 1-2 and 4-15 have been considered but are not persuasive. Applicant argues that Ishikawa does not cure the deficiency of the claim limitation, “the device further comprises a filter circuitry including a variable filter configured to allow the quantum signal having a wavelength to be adjusted to pass therethrough and not to allow the quantum signal having a wavelength other than the wavelength to be adjusted to pass therethrough (see Applicant’s Remarks, page 11). Examiner respectfully disagrees. The claim does not require that the variable filter be located on a transmission path. Ishikawa discloses a variable wavelength filter whose central wavelength is adjusted and through which the selected optical signal is received. A wavelength filter inherently allows signals at the selected wavelength to pass while rejecting others. Therefore, Examiner still rejects this limitations as the variable wavelength filter from the prior art discloses the claimed “filter circuitry including a variable filter” regardless of whether it is positioned on a reception path.
Applicant also argues that that the prior art does not teach the amended claim 1 nor claim 2’s limitation. Examiner respectfully disagrees. Kikawada 0036 teaches that the signal pulse trains, after passing through the attenuator 142, have a mean photon number per pulse. In the context of quantum key distribution systems, a mean photon number less than one is recognized as a single photon level output, which would satisfy the limitation of the external output being approximately 1 photon per pulse. Examiner also notes that because attenuation is a process that reduces signal intensity, the signal pulse trains entering the attenuator necessarily have a photon number greater than μ1, and therefore greater than one photon per pulse. See also 103 rejection below.
Therefore, the claimed limitations are still taught by Kikawada and Ishikawa.
Applicant amended claim 1, therefore the rejection has been resolved.
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.
Claims 1-2 and 4-15 are rejected under 35 U.S.C. 103 as being unpatentable over US 2020/0067601 A1 to Kikawada et al. (hereinafter, “Kikawada”) in view of US 2015/0016822 A1 to Ishikawa.
Kikawada discloses: A multiplexing device comprising:
The beam splitter 120 splits the intensity correction pulses 155, 156, and 157 according to the wavelengths. The intensity correction pulses 155, 156, and 157 originate in the light sources 102, 104, and 106, respectively, and thus have different wavelengths. The intensity correction pulse 155 is directed to the detector 122, the intensity correction pulse 156 is directed to the detector 124, and the intensity correction pulse 157 is directed to the detector 126. The beam splitter 120 is, but is not limited to, a wavelength beam splitter, such as a WDM” [0026])
transmitted from a plurality of quantum key distribution (QKD) devices (“The transmitter 100 includes light sources 102, 104, and 106, a controller 108, attenuators 110, 112, and 114, a beam combiner 116, a beam splitter 118, a beam splitter 120, detectors 122, 124, and 126, controllers 128, 130, and 132, an interferometer 134, and an attenuator 142. The light source 102 is connected to a first input port of the beam combiner 116 via the attenuator 110. The light source 104 is connected to a second input port of the beam combiner 116 via the attenuator 112. The light source 106 is connected to a third input port of the beam combiner 116 via the attenuator 114” [0015-0016]; “The beam combiner 116 combines the optical pulses 151, 152, and 153. The optical pulses 151, 152, and 153 enter the beam combiner 116 at different timings. The beam combiner 116 thereby outputs an optical pulse train 154 made of the optical pulses 151, 152, and 153 temporally separated. The beam combiner 116 is, but is not limited to, a wavelength combiner, such as a wavelength division multiplexer (WDM)” [0021] [Examiner notes that each light source emits a quantum signal (optical pulse) and each source has its own attenuator that is individually controlled by the controller 108, showing that each is a functionally separate transmitter path – as in, a separate QKD device. These independent optical paths are then combined using a beam combiner (e.g., a WDM), forming a wavelength-multiplexed signal – a technique commonly used to combine multiple QKD devices over one channel. The optical pulses 151, 152, and 153 (one from each light source) are referenced individually and repeatedly, showing that each contributes a distinct quantum signal and functionally represents a plurality of QKD transmitters]);
The beam splitter 118 splits the optical pulses 151, 152, and 153 output from the beam combiner 116 into two paths. The optical pulse output from the first output port of the beam splitter 118 is used for generation of an encryption key, and will be called a signal pulse. The optical pulse output from the second output port of the beam splitter 118 is used for correction of the intensities of the optical pulses output from the light sources 102, 104, and 106, and will be called an intensity correction pulse. The optical pulse 151 is split by the beam splitter 118 into an intensity correction pulse 155 and a signal pulse 158. The optical pulse 152 is split by the beam splitter 118 into an intensity correction pulse 156 and a signal pulse 159. The optical pulse 153 is split by the beam splitter 118 into an intensity correction pulse 157 and a signal pulse 160. The beam splitter 118 may be, but is not limited to, a fiber coupler. For example, another optical element may be used as the beam splitter 118. The branching ratio of the beam splitter 118 may be set so that the intensity of the intensity correction pulse is higher than the intensity of the signal pulse. The branching ratio may be 1:1 (i.e., the intensity of the intensity correction pulse may be set to be equal to the intensity of the signal pulse). The intensity of the intensity correction pulse may be set to be lower than the intensity of the signal pulse” [0024-0025] [Examiner notes that the branching circuity conducting the splitting is the beam splitter 118 as it divides the optical pulses. The input is a combined optical pulse train which is the wavelength multiplexed quantum signal since each pulse has a distinct wavelength. The branching ratio is set which confirms that the ratio is configurable and predetermined. Since one branch is used for intensity correction and the second is used for encryption key generation, the second would be the externally output quantum signal used in QKD]);
In the present embodiment, the detectors 122, 124, and 126 measure the intensities of incident light, and output detection signals indicative of the measured intensities to the respective controllers 128, 130, and 132. For example, when there is a disturbance in the intensity correction pulse 155, the intensity of the intensity correction pulse 155 measured at the detector 122 decreases. The controllers 128, 130, and 132 adjust the attenuators 110, 112, and 114 based on the detection signals so that the intensities of light incident on the detectors 122, 124, and 126 each have a target value. Accordingly, the optical pulses 151, 152, and 153 to be output from the light sources 102, 104, and 106 thereafter have the same intensity when entering the beam splitter 118. As a result, the signal pulses 158, 159, and 160 output from the beam splitter 118 have the same intensity. The controllers 128, 130, and 132 will be collectively referred to as an intensity controlling part. The attenuators 110, 112, and 114, the beam splitters 118 and 120, the detectors 122, 124, and 126, and the controllers 128, 130, and 132 will be collectively referred to as an intensity adjusting part” [0028] [Examiner notes that the light receiving circuitry is seen as the detectors here as they measure the intensities of light. The intensity correction pulse 155 is the branched part of the quantum signal that is used for measurement only. The output detection signals indicative of the measured intensities to the controllers display how a measurement result is acquired. Since the system uses these measurements to regulate future pulses strengthens the utility of the circuitry since its actively detecting – it is part of a closed feedback loop for intensity normalization which is valuable in these QKD systems where consistent signal strength is important for security and accuracy]); and
a processor configured to adjust intensity of the quantum signal output from each of the plurality of QKD devices based on the measurement result and the predetermined branching ratio (“In the present embodiment, the detectors 122, 124, and 126 measure the intensities of incident light, and output detection signals indicative of the measured intensities to the respective controllers 128, 130, and 132. For example, when there is a disturbance in the intensity correction pulse 155, the intensity of the intensity correction pulse 155 measured at the detector 122 decreases. The controllers 128, 130, and 132 adjust the attenuators 110, 112, and 114 based on the detection signals so that the intensities of light incident on the detectors 122, 124, and 126 each have a target value. Accordingly, the optical pulses 151, 152, and 153 to be output from the light sources 102, 104, and 106 thereafter have the same intensity when entering the beam splitter 118. As a result, the signal pulses 158, 159, and 160 output from the beam splitter 118 have the same intensity. The controllers 128, 130, and 132 will be collectively referred to as an intensity controlling part. The attenuators 110, 112, and 114, the beam splitters 118 and 120, the detectors 122, 124, and 126, and the controllers 128, 130, and 132 will be collectively referred to as an intensity adjusting part” [0028] [Examiner notes that the controllers act as processors as the each one processes feedback and issue control signals to adjust intensity. There is an active adjustment of quantum signal intensity from each source since there is a target value. The system includes multiple light sources, each forming a distinct quantum channel or QKD device. It is adjusted based on the measurement result and the predetermined branching ratio because it uses the detection signals which is a direct use of measurement results for adjustment and it explicitly acknowledges the branching ratio as the processer (controller) adjusts the intensities while accounting for how the signal is split]),
wherein wavelengths of the quantum signals transmitted from the plurality of QKD devices are different from each other (“The beam splitter 120 splits the intensity correction pulses 155, 156, and 157 according to the wavelengths. The intensity correction pulses 155, 156, and 157 originate in the light sources 102, 104, and 106, respectively, and thus have different wavelengths” [0026]),
the processor is configured to adjust intensity of the quantum signal to be output from the branching circuitry to the external to become one photon per pulse by making the intensity of the quantum signal to be output from each of the plurality of QKD devices to be greater than one photon per pulse and thereby making intensity of the quantum signal between each of the plurality of QKD devices and the branching circuitry to be greater than one photon per pulse (“The signal pulse trains 161 and 165 output from the interferometer 134 enter the attenuator 142. The attenuator 142 attenuates the signal pulse trains 161 and 165 so that the intensities of the signal pulse trains 161 and 165 is at a single photon level. Specifically, the attenuator 142 attenuates the signal pulse trains 161 and 165 so that the mean number of photons per pulse of each of the signal pulses 162, 163, 164, 166, 167, and 168 is smaller than one. Where the mean number of photons per pulse of each signal pulse after attenuation is μ1, μ1<1. For example, μ1=0.5. The signal pulse trains 161 and 165 that have passed the attenuator 142 enter the transmission path 190, and are transmitted to the receiver 200 through the transmission path 190 as the signal pulse train 169. In this example, the output port of the attenuator 142 corresponds to a transmitting part that transmits the signal pulse train 169 to the receiver 200” [0036] [Examiner notes that this text explicitly discloses that the signal pulse trains, after passing through the attenuator 142, have a mean photon number per pulse. In the context of quantum key distribution systems, a mean photon number less than one is recognized as a single photon level output, which would satisfy the limitation of the external output being approximately 1 photon per pulse. Examiner also notes that because attenuation is a process that reduces signal intensity, the signal pulse trains entering the attenuator necessarily have a photon number greater than μ1, and therefore greater than one photon per pulse]).
Kikawada does not explicitly disclose: the device further comprises a filter circuitry including a variable filter configured to allow the quantum signal having a wavelength to be adjusted to pass therethrough and not to allow the quantum signal having a wavelength other than the wavelength to be adjusted to pass therethrough, and
However, Ishikawa discloses: the device further comprises a filter circuitry including a variable filter configured to allow a quantum signal having a wavelength to be adjusted to pass therethrough and not to allow a quantum signal having a wavelength other than the wavelength to be adjusted to pass therethrough (“When the determined ratio P0/P1 is smaller than the reference ratio P0/P2, the calculation unit 34A sends, to the adjuster 25A, a second adjustment signal for adjusting the filter band for the variable-wavelength filter 23A corresponding to that adjacent channel in the frequency-increasing direction. The second adjustment signal includes an adjustment amount by which the central wavelength in the adjacent channel is to be shifted and adjusted in the frequency-increasing direction and also identification information for identifying the variable-wavelength filter 23A which corresponds to the adjacent channel and for which the filter band is to be adjusted. Based on the identification information in the second adjustment signal from the controller 24A, the adjuster 25A identifies the variable-wavelength filter 23A which corresponds to the adjacent channel and for which the filter band is to be adjusted. Based on the adjustment amount in the second adjustment signal, the adjuster 25A adjusts the filter band for the identified variable-wavelength filter 23A. Following the adjacent channel for which the transmission node 2 has adjusted the wavelength spacing in the frequency-increasing direction, the optical receiver 23B receives an optical signal in that adjacent channel” [0074-0075] [Examiner notes that this system explicitly names a “variable-wavelength filter 23A” which is a variable filter. The “filter band adjustment confirms active control (mirrors core feature of a variable or tunable filter. The adjustment of the central wavelength defines the wavelength that can pass. When the filter’s band is adjusted, only signals at that new wavelength can pass which shows allowing a quantum signal having a wavelength to be adjusted to pass. By tuning the filter band for a specific wavelength, the filter inherently blocks other wavelengths outside the adjusted band. This is standard in variable optical filtering as the filter band defines both what passes and what is rejected]), and
Thus, it 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, to combine the
method of Kikawada with the added structure of Ishikawa in order to control what type of quantum signal/wavelength can pass through on to the next path.
Regarding claim 2, a combination of Kikawada-Ishikawa discloses all limitations of claim 1.
Furthermore, Kikawada discloses: wherein the processor is configured to adjust the intensity of the quantum signal to be output from each of the plurality of QKD devices so that the quantum signal of each of the plurality of QKD devices to be output to the external of the multiplexing device is one photon per pulse (“The signal pulse trains 161 and 165 output from the interferometer 134 enter the attenuator 142. The attenuator 142 attenuates the signal pulse trains 161 and 165 so that the intensities of the signal pulse trains 161 and 165 is at a single photon level. Specifically, the attenuator 142 attenuates the signal pulse trains 161 and 165 so that the mean number of photons per pulse of each of the signal pulses 162, 163, 164, 166, 167, and 168 is smaller than one. Where the mean number of photons per pulse of each signal pulse after attenuation is μ1, μ1<1. For example, μ1=0.5. The signal pulse trains 161 and 165 that have passed the attenuator 142 enter the transmission path 190, and are transmitted to the receiver 200 through the transmission path 190 as the signal pulse train 169. In this example, the output port of the attenuator 142 corresponds to a transmitting part that transmits the signal pulse train 169 to the receiver 200” [0036] [Examiner notes that since the mean number of photons per pulse of each signal pulse after attenuation is μ1<1, some pulses contain 1 photon while other contains 0 or more than 1 photon, consistent with single photon level output. Although the text discloses a mean photon number μ1<1 for example, μ1=0.5, in the field of quantum key distribution systems, a mean photon number less than 1 is recognized as single photon level output. Therefore, the output described in the prior art teaches that the quantum signal is one photon per pulse. Furthermore, since the attenuation reduces the intensity of the incoming signal, the pre-attenuation signals necessarily have photon numbers greater than 1, supporting the internal intensity requirement]).
Regarding claim 4, Kikawada discloses: A QKD system comprising:
the multiplexing device according to claim 1 (“a quantum key distribution system including a transmitter (transmitting apparatus) 100 and a receiver (receiving apparatus) 200 according to the first embodiment” [0013] [Examiner interprets the system including the transmitter which is the multiplexing device]); and
the plurality of QKD devices according to claim 1 (“The transmitter 100 includes light sources 102, 104, and 106, a controller 108, attenuators 110, 112, and 114, a beam combiner 116, a beam splitter 118, a beam splitter 120, detectors 122, 124, and 126, controllers 128, 130, and 132, an interferometer 134, and an attenuator 142. The light source 102 is connected to a first input port of the beam combiner 116 via the attenuator 110. The light source 104 is connected to a second input port of the beam combiner 116 via the attenuator 112. The light source 106 is connected to a third input port of the beam combiner 116 via the attenuator 114” [0015-0016]; “The beam combiner 116 combines the optical pulses 151, 152, and 153. The optical pulses 151, 152, and 153 enter the beam combiner 116 at different timings. The beam combiner 116 thereby outputs an optical pulse train 154 made of the optical pulses 151, 152, and 153 temporally separated. The beam combiner 116 is, but is not limited to, a wavelength combiner, such as a wavelength division multiplexer (WDM)” [0021] [Examiner notes that each light source emits a quantum signal (optical pulse) and each source has its own attenuator that is individually controlled by the controller 108, showing that each is a functionally separate transmitter path – as in, a separate QKD device. These independent optical paths are then combined using a beam combiner (e.g., a WDM), forming a wavelength-multiplexed signal – a technique commonly used to combine multiple QKD devices over one channel. The optical pulses 151, 152, and 153 (one from each light source) are referenced individually and repeatedly, showing that each contributes a distinct quantum signal and functionally represents a plurality of QKD transmitters]).
Regarding claim 5, Kikawada discloses: A quantum key distribution (QKD) device connected to a multiplexing device, the QKD device comprising:
a light source configured to transmit a quantum signal (“The light sources 102, 104, and 106 generate optical pulses 151, 152, and 153, respectively” [0019]; “Specifically, the attenuator 142 attenuates the signal pulse trains 161 and 165 so that the mean number of photons per pulse of each of the signal pulses 162, 163, 164, 166, 167, and 168 is smaller than one... The signal pulse trains 161 and 165 that have passed the attenuator 142 enter the transmission path 190, and are transmitted to the receiver 200 through the transmission path 190 as the signal pulse train 169” [0036] [Examiner notes that the light sources generate optical pulses which are the origin of the quantum signal. The optical pulses are turned into quantum signals and are then transmitted]); and
a processor configured to adjust intensity of a quantum signal transmitted from the light source (“The controllers 128, 130, and 132 adjust the attenuators 110, 112, and 114 based on the detection signals so that the intensities of light incident on the detectors 122, 124, and 126 each have a target value” [0028] [Examiner notes that the controllers act as processors as the each one processes feedback and issue control signals to adjust intensity. There is an active adjustment of quantum signal intensity from each source since there is a target value. The system includes multiple light sources, each forming a distinct quantum channel or QKD device. It is adjusted based on the measurement result and the predetermined branching ratio because it uses the detection signals which is a direct use of measurement results for adjustment and it explicitly acknowledges the branching ratio as the processer (controller) adjusts the intensities while accounting for how the signal is split]),
based on a predetermined branching ratio (“The beam splitter 118 splits the optical pulses 151, 152, and 153 output from the beam combiner 116 into two paths. The optical pulse output from the first output port of the beam splitter 118 is used for generation of an encryption key, and will be called a signal pulse. The optical pulse output from the second output port of the beam splitter 118 is used for correction of the intensities of the optical pulses output from the light sources 102, 104, and 106, and will be called an intensity correction pulse. The optical pulse 151 is split by the beam splitter 118 into an intensity correction pulse 155 and a signal pulse 158. The optical pulse 152 is split by the beam splitter 118 into an intensity correction pulse 156 and a signal pulse 159. The optical pulse 153 is split by the beam splitter 118 into an intensity correction pulse 157 and a signal pulse 160. The beam splitter 118 may be, but is not limited to, a fiber coupler. For example, another optical element may be used as the beam splitter 118. The branching ratio of the beam splitter 118 may be set so that the intensity of the intensity correction pulse is higher than the intensity of the signal pulse. The branching ratio may be 1:1 (i.e., the intensity of the intensity correction pulse may be set to be equal to the intensity of the signal pulse). The intensity of the intensity correction pulse may be set to be lower than the intensity of the signal pulse” [0024-0025] [Examiner notes that the branching circuity conducting the splitting is the beam splitter 118 as it divides the optical pulses. The input is a combined optical pulse train which is the wavelength multiplexed quantum signal since each pulse has a distinct wavelength. The branching ratio is set which confirms that the ratio is configurable and predetermined. Since one branch is used for intensity correction and the second is used for encryption key generation, the second would be the externally output quantum signal used in QKD]) and
intensity of a quantum signal to be measured (“In the present embodiment, the detectors 122, 124, and 126 measure the intensities of incident light, and output detection signals indicative of the measured intensities to the respective controllers 128, 130, and 132. For example, when there is a disturbance in the intensity correction pulse 155, the intensity of the intensity correction pulse 155 measured at the detector 122 decreases. The controllers 128, 130, and 132 adjust the attenuators 110, 112, and 114 based on the detection signals so that the intensities of light incident on the detectors 122, 124, and 126 each have a target value. Accordingly, the optical pulses 151, 152, and 153 to be output from the light sources 102, 104, and 106 thereafter have the same intensity when entering the beam splitter 118. As a result, the signal pulses 158, 159, and 160 output from the beam splitter 118 have the same intensity. The controllers 128, 130, and 132 will be collectively referred to as an intensity controlling part. The attenuators 110, 112, and 114, the beam splitters 118 and 120, the detectors 122, 124, and 126, and the controllers 128, 130, and 132 will be collectively referred to as an intensity adjusting part” [0028] [Examiner notes that the light receiving circuitry is seen as the detectors here as they measure the intensities of light. The intensity correction pulse 155 is the branched part of the quantum signal that is used for measurement only. The output detection signals indicative of the measured intensities to the controllers display how a measurement result is acquired. Since the system uses these measurements to regulate future pulses strengthens the utility of the circuitry since its actively detecting – it is part of a closed feedback loop for intensity normalization which is valuable in these QKD systems where consistent signal strength is important for security and accuracy])
branched at the predetermined branching ratio (“The beam splitter 118 splits the optical pulses 151, 152, and 153 output from the beam combiner 116 into two paths... The optical pulse 151 is split by the beam splitter 118 into an intensity correction pulse 155 and a signal pulse 158. The optical pulse 152 is split by the beam splitter 118 into an intensity correction pulse 156 and a signal pulse 159. The optical pulse 153 is split by the beam splitter 118 into an intensity correction pulse 157 and a signal pulse 160... The branching ratio of the beam splitter 118 may be set so that the intensity of the intensity correction pulse is higher than the intensity of the signal pulse. The branching ratio may be 1:1 (i.e., the intensity of the intensity correction pulse may be set to be equal to the intensity of the signal pulse)” [0024-0025]),
from a quantum signal obtained by optical wavelength multiplexing of a quantum signal transmitted from another QKD device connected to the multiplexing device and the quantum signal transmitted from the light source (“As described above, the transmitter 100 modulates signal pulses having different wavelengths by one modulator 138, and the receiver 200 modulates signal pulses having different wavelengths by one modulator 208. This enables avoidance of complication of the apparatus and reduction of the apparatus cost, in comparison with the case where modulators equal in number to wavelengths are provided in each of the transmitter and the receiver” [0071]; “The beam combiner 140 combines the signal pulse train 161 modulated in phase by the modulator 138 with the signal pulse train 165. The slow axis of the polarization-maintaining fiber connected to the second input port of the beam combiner 140 is rotated by 90° with respect to the slow axis of the polarization-maintaining fiber connected to the first input port of the beam combiner 140. The polarizations of the signal pulses 162, 163, and 164 are thereby made orthogonal to those of the signal pulses 166, 167, and 168. The beam combiner 140 may be, but is not limited to, a polarization beam splitter” [0034] [Examiner notes that these texts shows the modulation of multiple wavelengths from multiple QKD devices/channels before combining and the beam combiner 140 that multiplexes (combines) multiple quantum signals into one output (the topical wavelength multiplexing]),
wherein a wavelength of the quantum signal transmitted from the light source is different from a wavelength of the quantum signal transmitted form anther QKD device (“The beam splitter 120 splits the intensity correction pulses 155, 156, and 157 according to the wavelengths. The intensity correction pulses 155, 156, and 157 originate in the light sources 102, 104, and 106, respectively, and thus have different wavelengths” [0026]), and
the processor is configured to adjust intensity of the quantum signal to be output from the multiplexing device to an external to become one photon per pulse by making intensity of the quantum signal to be output from the QKD device to be greater than one photon per pulse and thereby making intensity of the quantum signal between the QKD device and the multiplexing device to be greater than one photon per pulse (“The signal pulse trains 161 and 165 output from the interferometer 134 enter the attenuator 142. The attenuator 142 attenuates the signal pulse trains 161 and 165 so that the intensities of the signal pulse trains 161 and 165 is at a single photon level. Specifically, the attenuator 142 attenuates the signal pulse trains 161 and 165 so that the mean number of photons per pulse of each of the signal pulses 162, 163, 164, 166, 167, and 168 is smaller than one. Where the mean number of photons per pulse of each signal pulse after attenuation is μ1, μ1<1. For example, μ1=0.5. The signal pulse trains 161 and 165 that have passed the attenuator 142 enter the transmission path 190, and are transmitted to the receiver 200 through the transmission path 190 as the signal pulse train 169. In this example, the output port of the attenuator 142 corresponds to a transmitting part that transmits the signal pulse train 169 to the receiver 200” [0036] [Examiner notes that this text explicitly discloses that the signal pulse trains, after passing through the attenuator 142, have a mean photon number per pulse . In the context of quantum key distribution systems, a mean photon number less than one is recognized as a single photon level output, which would satisfy the limitation of the external output being approximately 1 photon per pulse. Examiner also notes that because attenuation is a process that reduces signal intensity, the signal pulse trains entering the attenuator necessarily have a photon number greater than μ1, and therefore greater than one photon per pulse]).
Kikawada does not explicitly disclose: the multiplexing device comprises a filter circuitry including a variable filter configured to allow the quantum signal having a wavelength to be adjusted to pass therethrough and not to allow the quantum signal having a wavelength other than the wavelength to be adjusted to pass therethrough, and
However, Ishikawa discloses: the multiplexing device comprises a filter circuitry including a variable filter configured to allow a quantum signal having a wavelength to be adjusted to pass therethrough and not to allow a quantum signal having a wavelength other than the wavelength to be adjusted to pass therethrough (“When the determined ratio P0/P1 is smaller than the reference ratio P0/P2, the calculation unit 34A sends, to the adjuster 25A, a second adjustment signal for adjusting the filter band for the variable-wavelength filter 23A corresponding to that adjacent channel in the frequency-increasing direction. The second adjustment signal includes an adjustment amount by which the central wavelength in the adjacent channel is to be shifted and adjusted in the frequency-increasing direction and also identification information for identifying the variable-wavelength filter 23A which corresponds to the adjacent channel and for which the filter band is to be adjusted. Based on the identification information in the second adjustment signal from the controller 24A, the adjuster 25A identifies the variable-wavelength filter 23A which corresponds to the adjacent channel and for which the filter band is to be adjusted. Based on the adjustment amount in the second adjustment signal, the adjuster 25A adjusts the filter band for the identified variable-wavelength filter 23A. Following the adjacent channel for which the transmission node 2 has adjusted the wavelength spacing in the frequency-increasing direction, the optical receiver 23B receives an optical signal in that adjacent channel” [0074-0075] [Examiner notes that this system explicitly names a “variable-wavelength filter 23A” which is a variable filter. The “filter band adjustment confirms active control (mirrors core feature of a variable or tunable filter. The adjustment of the central wavelength defines the wavelength that can pass. When the filter’s band is adjusted, only signals at that new wavelength can pass which shows allowing a quantum signal having a wavelength to be adjusted to pass. By tuning the filter band for a specific wavelength, the filter inherently blocks other wavelengths outside the adjusted band. This is standard in variable optical filtering as the filter band defines both what passes and what is rejected]).
Thus, it 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, to combine the
method of Kikawada with the added structure of Ishikawa in order to control what type of quantum signal/wavelength can pass through on to the next path.
Regarding claim 6, a combination of Kikawada-Ishikawa discloses all limitations of claim 5.
Furthermore, Kikawada discloses: wherein the processor is configured to receive a measurement result of the intensity of the quantum signal to be measured from the multiplexing device, and adjust the intensity of the quantum signal transmitted from the light source based on the measurement result and the predetermined branching ratio (“In the present embodiment, the detectors 122, 124, and 126 measure the intensities of incident light, and output detection signals indicative of the measured intensities to the respective controllers 128, 130, and 132. For example, when there is a disturbance in the intensity correction pulse 155, the intensity of the intensity correction pulse 155 measured at the detector 122 decreases. The controllers 128, 130, and 132 adjust the attenuators 110, 112, and 114 based on the detection signals so that the intensities of light incident on the detectors 122, 124, and 126 each have a target value. Accordingly, the optical pulses 151, 152, and 153 to be output from the light sources 102, 104, and 106 thereafter have the same intensity when entering the beam splitter 118. As a result, the signal pulses 158, 159, and 160 output from the beam splitter 118 have the same intensity. The controllers 128, 130, and 132 will be collectively referred to as an intensity controlling part. The attenuators 110, 112, and 114, the beam splitters 118 and 120, the detectors 122, 124, and 126, and the controllers 128, 130, and 132 will be collectively referred to as an intensity adjusting part” [0028] [Examiner notes that the controllers act as processors as the each one processes feedback and issue control signals to adjust intensity. There is an active adjustment of quantum signal intensity from each source since there is a target value. The system includes multiple light sources, each forming a distinct quantum channel or QKD device. It is adjusted based on the measurement result and the predetermined branching ratio because it uses the detection signals which is a direct use of measurement results for adjustment and it explicitly acknowledges the branching ratio as the processer (controller) adjusts the intensities while accounting for how the signal is split]).
Claim 7 recites substantially the same limitation as claim 1, in the form of a device for implementing the corresponding method, therefore it is rejected under the same rationale.
Claim 8 recites substantially the same limitation as claim 1, in the form of a multiplexing method for implementing the corresponding method, therefore it is rejected under the same rationale.
Claim 9 recites substantially the same limitation as claim 5, in the form of an adjustment method for implementing the corresponding method, therefore it is rejected under the same rationale.
Regarding claim 10, a combination of Kikawada-Ishikawa discloses all limitations of claim 1.
Kikawada does not disclose: wherein the light receiving circuitry is configured to receive the quantum signal having the wavelength to be adjusted from the filter circuitry.
However, Ishikawa discloses: wherein the light receiving circuitry is configured to receive the quantum signal having the wavelength to be adjusted from the filter circuitry (“Following the adjacent channel for which the transmission node 2 has adjusted the wavelength spacing in the frequency-increasing direction, the optical receiver 23B receives an optical signal in that adjacent channel” [0075] [Examiner notes that optical receiver 23B is the light receiving circuitry that receives the signal. The adjacent channel corresponds to the specific wavelength that was selected/tunes by the filter]).
Thus, it 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, to combine the
method of Kikawada with the added structure of Ishikawa in order to control what type of quantum signal/wavelength can pass through on to the next path.
Regarding claim 11, a combination of Kikawada-Ishikawa discloses all limitations of claim 1.
Furthermore, Ishikawa discloses: wherein the filter circuitry is configured to receive the quantum signal to be measured Following the adjacent channel for which the transmission node 2 has adjusted the wavelength spacing in the frequency-increasing direction, the optical receiver 23B receives an optical signal in that adjacent channel” [0075] [Examiner notes that optical receiver 23B is the light receiving circuitry that receives the signal. The adjacent channel corresponds to the specific wavelength that was selected/tunes by the filter]).
Ishikawa does not disclose: wherein the filter circuitry is configured to receive the quantum signal to be measured from the branching circuitry.
However, Kikawada discloses: wherein the filter circuitry is configured to receive the quantum signal to be measured from the branching circuitry (“The output port of the beam combiner 116 is connected to the input port of the beam splitter 118. A first output port of the beam splitter 118 is connected to the transmission path 190 via the interferometer 134 and the attenuator 142, and a second output port of the beam splitter 118 is connected to the input port of the beam splitter 120” [0016] [Examiner notes that these beam splitters are seen as the branching circuitry that direct quantum signals along specific paths, whether it is for measurement/detection, or to the filter circuitry in order for the quantum signal to be measured]).
Thus, it 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, to combine the
method of Kikawada with the added structure of Ishikawa in order to control what type of quantum signal/wavelength can pass through on to the next path.
Claim 12 recites substantially the same limitation as claim 10, in the form of a device for implementing the corresponding device, therefore it is rejected under the same rationale.
Claim 13 recites substantially the same limitation as claim 11, in the form of a device for implementing the corresponding device, therefore it is rejected under the same rationale.
Regarding claim 14, a combination of Kikawada-Ishikawa discloses all limitations of claim 8.
Kikawada does not disclose: wherein quantum signal to be measured is the quantum signal having the wavelength to be adjusted.
However, Ishikawa discloses: wherein quantum signal to be measured is the quantum signal having the wavelength to be adjusted (“Following the adjacent channel for which the transmission node 2 has adjusted the wavelength spacing in the frequency-increasing direction, the optical receiver 23B receives an optical signal in that adjacent channel” [0075] [Examiner notes that the optical receiver 23B receives signals and measures the signals it receives. The adjacent channel represents the specific wavelength that was selected/adjusted by the variable-wavelength filter 23A]).
Thus, it 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, to combine the
method of Kikawada with the added structure of Ishikawa in order to control what type of quantum signal/wavelength can pass through on to the next path and/or select the specific wavelength to advance to the next step.
Claim 15 recites substantially the same limitation as claim 14, in the form of an adjustment method for implementing the corresponding multiplexing method, therefore it is rejected under the same rationale.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant’s disclosure:
Arahira (US 8433200 B2) teaches techniques of a quantum key delivery system that includes an optical circulator, an optical low-pass filter, optical splitters, and first and second optical couplers arranged for outputting various wavelength components including correlated-photon pair wavelength components outputted from an optical loop path. The first and second optical couplers output light beams, which are sent over first and second quantum channels to first and second recipients, respectively. Other optical splitters are adapted to output light rays, from which first and second control signals are produced. From auxiliary idler light components transmitted over the first and second quantum channels, clock signals are extracted. The system thus extracts a clock signal for detecting arrival of photons, and stably operates with an expected value of the number of generated correlated photon pairs maintained at a substantially constant value.
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/SARON MATTHEWOS WORKU/Examiner, Art Unit 2408
/LINGLAN EDWARDS/Supervisory Patent Examiner, Art Unit 2408