# US 12,113,578 B2 · Optical sender and method for deciding modulation timing correctness > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,113,578 B2 - Document ID: US12113578B2 - Status: Granted - Kind: B2 - Application number: 18/009,145 - Filed: 2020-06-10 - Published: 2023-08-10 - Granted: 2024-10-08 - Earliest claimed: 2020-06-10 - Assignees: NEC Corporation - Applicants: NEC Corporation - Inventors: Ken-ichiro Yoshino - Web page: https://patentgrep.com/patent/US12113578B2 ## CPC - H04B 10/524: Pulse modulation - H04B 10/5059: {using a feed-forward signal generated by analysing the optical or electrical input} - H04B 10/508: Pulse generation, e.g. generation of solitons - H04B 10/54: Intensity modulation - H04B 17/201: {for measurement of specific parameters of the receiver or components thereof} - H04L 9/12: Transmitting and receiving encryption devices synchronised or initially set up in a particular manner - H04B 10/70: Photonic quantum communication - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract An optical sender is disclosed, which alone makes it possible to reliably decide whether modulation timing is correct or incorrect and to adjust the modulation timing. The optical sender includes: a first modulator that outputs a first optical pulse train subjected to intensity modulation; an asymmetric interferometer that outputs a second optical pulse train of double pulses; a second modulator (104) that outputs a third optical pulse train subjected to send-data modulation for each pulse pair; nd an optical intensity measuring device that measures an optical intensity of the third optical pulse train, a controller, when changing either of a first optical pulse train according to intensity modulation pattern and a second optical pulse train according to send-data modulation pattern, decides whether the modulation timing is correct or incorrect, based on optical intensity of the third optical pulse train. ## Claims ### Claim 1 An optical sender that modulates an optical pulse train having a predetermined period for data sending, comprising: a first modulator that performs intensity modulation on the optical pulse train to output a first optical pulse train, wherein the intensity modulation is performed at least between a reference intensity and a zero intensity; an asymmetric interferometer that inputs the first optical pulse train and outputs a second optical pulse train of double pulses, wherein each double pulse is generated by temporally separating each optical pulse of the first optical pulse train; a second modulator that performs send-data modulation for each pulse pair of the second optical pulse train to output a third optical pulse train; an optical intensity monitor that measures an optical intensity of the third optical pulse train; and a controller configured to: a) control the intensity modulation of the first modulator for generating each double pulse of the second optical pulse train having the reference intensity or the zero intensity depending on the intensity modulation according to an intensity modulation pattern; b) control the send-data modulation of the second modulator for generating each pulse pair of the second optical pulse train with either pulse of the pulse pair having the zero intensity depending on the send-data modulation according to a send-data modulation pattern; and c) decide whether or not the pulse pair is the double pulse, based on an optical intensity of the third optical pulse train when changing either of the intensity modulation pattern and the send-data modulation pattern. ### Claim 2 (depends on 1) The optical sender according to claim 1, wherein the optical intensity monitor measures an average optical intensity of the third optical pulse train. ### Claim 3 (depends on 1) The optical sender according to claim 1, wherein, in the c), the controller is configured to: change either of the intensity modulation pattern and the send-data modulation pattern; and decide whether or not the pulse pair is the double pulse, based on a comparison result between a first optical intensity of the third optical pulse train before pattern change and a second optical intensity of the third optical pulse train after pattern change. ### Claim 4 (depends on 1) The optical sender according to claim 1, wherein, assuming that the optical pulse train has the reference intensity, the intensity modulation pattern includes a first intensity modulation pattern and a second intensity modulation pattern, wherein the first intensity modulation pattern causes the second optical pulse train to repeat a double pulse of the reference intensity, wherein the second intensity modulation pattern causes the second optical pulse train to repeat the reference intensity and the zero intensity every other double pulse by the optical pulse train repeatedly alternating between the reference intensity and the zero intensity every other pulse, the send-data modulation pattern includes a first send-data modulation pattern and a second send-data modulation pattern which alternate repeatedly, wherein the first send-data modulation pattern causes one pulse of the pulse pair to have zero intensity and the other pulse to have the reference intensity, wherein the second send-data modulation pattern causes the one pulse of the pulse pair to have the reference intensity and the other pulse to have the zero intensity, in the c), the controller is configured to decide whether or not the pulse pair is the double pulse, by comparing a first optical intensity of the third optical pulse train with a second optical intensity of the third optical pulse train, wherein the first optical intensity is measured when the send-data modulation pattern is fixed and the intensity modulation pattern is set at the first intensity modulation pattern, wherein the second optical intensity is measured when the intensity modulation pattern is changed to the second intensity modulation patten. ### Claim 5 (depends on 1) The optical sender according to claim 1, wherein the intensity modulation pattern causes the second optical pulse train to repeat the reference intensity and the zero intensity every other double pulse by the optical pulse train repeatedly alternating between the reference intensity and the zero intensity every other pulse, the send-data modulation pattern includes a first send-data modulation pattern and a second send-data modulation pattern which alternate repeatedly, wherein the first send-data modulation pattern causes one pulse of the pulse pair to have zero intensity and the other pulse to have the reference intensity, wherein the second send-data modulation pattern causes the one pulse of the pulse pair to have the reference intensity and the other pulse to have the zero intensity, in the c), the controller is configured to decide whether or not the pulse pair is the double pulse, by comparing a first optical intensity of the third optical pulse train with a second optical intensity of the third optical pulse train, wherein the first optical intensity is measured when one pattern of the intensity modulation pattern and the send-data modulation pattern is fixed and the other pattern is set at a predetermined pattern, wherein the second optical intensity is measured when the other pattern is inverted. ### Claim 6 (depends on 1) The optical sender according to claim 1, wherein the first modulator is an intensity modulator that performs intensity modulation according to a decoy state method, the second modulator is an intensity-phase modulator that performs phase modulation on the pulse pair or intensity modulation such that any one pulse of the pulse pair has zero intensity according to the send data, and the optical intensity measuring device uses an optical detector that monitors the optical intensity of the third optical pulse train, wherein in the c), the controller is configured to adjust modulation timing of the second modulator such that the pulse pair becomes the double pulse. ### Claim 7 A method for deciding whether modulation timing correctness in an optical sender that modulates an optical pulse train having a predetermined period for data sending, the method comprising: by a first modulator, performing intensity modulation on the optical pulse train to output a first optical pulse train, wherein the intensity modulation is performed at least between a reference intensity and a zero intensity; by an asymmetric interferometer, inputting the first optical pulse train and outputting a second optical pulse train of double pulses, wherein each double pulse is generated by temporally separating each optical pulse of the first optical pulse train; by a second modulator, performing send-data modulation for each pulse pair of the second optical pulse train to output a third optical pulse train; by an optical intensity measuring device, measuring an optical intensity of the third optical pulse train; and by a controller, a) controlling the intensity modulation of the first modulator for generating each double pulse of the second optical pulse train having the reference intensity or the zero intensity depending on the intensity modulation according to an intensity modulation pattern; b) controlling the send-data modulation of the second modulator for generating each pulse pair of the second optical pulse train with either pulse of the pulse pair having the zero intensity depending on the send-data modulation according to a send-data modulation pattern; and c) deciding whether or not the pulse pair is the double pulse, based on an optical intensity of the third optical pulse train when changing either of the intensity modulation pattern and the send-data modulation pattern. ### Claim 8 (depends on 7) The method according to claim 7, wherein the optical intensity monitor measures an average optical intensity of the third optical pulse train. ### Claim 9 (depends on 7) The method according to claim 7, wherein, the c) comprises: changing either of the intensity modulation pattern and the send-data modulation pattern; and deciding whether or not the pulse pair is the double pulse, based on a comparison result between a first optical intensity of the third optical pulse train before pattern change and a second optical intensity of the third optical pulse train after pattern change. ### Claim 10 (depends on 7) The method according to claim 7, wherein, assuming that the optical pulse train has the reference intensity, the intensity modulation pattern includes a first intensity modulation pattern and a second intensity modulation pattern, wherein the first intensity modulation pattern causes the second optical pulse train to repeat a double pulse of the reference intensity, wherein the second intensity modulation pattern causes the second optical pulse train to repeat the reference intensity and the zero intensity every other double pulse by the optical pulse train repeatedly alternating between the reference intensity and the zero intensity every other pulse, the send-data modulation pattern includes a first send-data modulation pattern and a second send-data modulation pattern which alternate repeatedly, wherein the first send-data modulation pattern causes one pulse of the pulse pair to have zero intensity and the other pulse to have the reference intensity, wherein the second send-data modulation pattern causes the one pulse of the pulse pair to have the reference intensity and the other pulse to have the zero intensity, the c) comprises: deciding whether or not the pulse pair is the double pulse, by comparing a first optical intensity of the third optical pulse train with a second optical intensity of the third optical pulse train, wherein the first optical intensity is measured when the send-data modulation pattern is fixed and the intensity modulation pattern is set at the first intensity modulation pattern, wherein the second optical intensity is measured when the intensity modulation pattern is changed to the second intensity modulation patten. ### Claim 11 (depends on 7) The method according to claim 7, wherein the intensity modulation pattern causes the second optical pulse train to repeat the reference intensity and the zero intensity every other double pulse by the optical pulse train repeatedly alternating between the reference intensity and the zero intensity every other pulse, the send-data modulation pattern includes a first send-data modulation pattern and a second send-data modulation pattern which alternate repeatedly, wherein the first send-data modulation pattern causes one pulse of the pulse pair to have zero intensity and the other pulse to have the reference intensity, wherein the second send-data modulation pattern causes the one pulse of the pulse pair to have the reference intensity and the other pulse to have the zero intensity, the c) comprises: deciding whether or not the pulse pair is the double pulse, by comparing a first optical intensity of the third optical pulse train with a second optical intensity of the third optical pulse train, wherein the first optical intensity is measured when one pattern of the intensity modulation pattern and the send-data modulation pattern is fixed and the other pattern is set at a predetermined pattern, wherein the second optical intensity is measured when the other pattern is inverted. ### Claim 12 A non-transitory computer readable storage medium storing a program for functioning a computer as a controller of an optical sender including: a first modulator that performs intensity modulation on the optical pulse train to output a first optical pulse train, wherein the intensity modulation is performed at least between a reference intensity and a zero intensity; an asymmetric interferometer that inputs the first optical pulse train and outputs a second optical pulse train of double pulses, wherein each double pulse is generated by temporally separating each optical pulse of the first optical pulse train; a second modulator that performs send-data modulation for each pulse pair of the second optical pulse train to output a third optical pulse train; and an optical intensity monitor that measures an optical intensity of the third optical pulse train, the program which, when executed by a processor of the optical sender, performs a method comprising: a) generating each double pulse of the second optical pulse train having the reference intensity or the zero intensity depending on the intensity modulation according to an intensity modulation pattern; b) generating each pulse pair of the second optical pulse train with either pulse of the pulse pair having the zero intensity depending on the send-data modulation according to a send-data modulation pattern; and c) deciding whether or not the pulse pair is the double pulse, based on an optical intensity of the third optical pulse train when changing either of the intensity modulation pattern and the send-data modulation pattern. ### Claim 13 (depends on 12) The non-transitory computer readable storage medium according to claim 12, wherein the optical intensity monitor measures an average optical intensity of the third optical pulse train. ### Claim 14 (depends on 12) The non-transitory computer readable storage medium according to claim 12, wherein the c) comprises: changing either of the intensity modulation pattern and the send-data modulation pattern; and deciding whether or not the pulse pair is the double pulse, based on a comparison result between a first optical intensity of the third optical pulse train before pattern change and a second optical intensity of the third optical pulse train after pattern change. ### Claim 15 (depends on 12) The non-transitory computer readable storage medium according to claim 12, wherein, assuming that the optical pulse train has the reference intensity, the intensity modulation pattern includes a first intensity modulation pattern and a second intensity modulation pattern, wherein the first intensity modulation pattern causes the second optical pulse train to repeat a double pulse of the reference intensity, wherein the second intensity modulation pattern causes the second optical pulse train to repeat the reference intensity and the zero intensity every other double pulse by the optical pulse train repeatedly alternating between the reference intensity and the zero intensity every other pulse, the send-data modulation pattern includes a first send-data modulation pattern and a second send-data modulation pattern which alternate repeatedly, wherein the first send-data modulation pattern causes one pulse of the pulse pair to have zero intensity and the other pulse to have the reference intensity, wherein the second send-data modulation pattern causes the one pulse of the pulse pair to have the reference intensity and the other pulse to have the zero intensity, the c) comprises: deciding whether or not the pulse pair is the double pulse, by comparing a first optical intensity of the third optical pulse train with a second optical intensity of the third optical pulse train, wherein the first optical intensity is measured when the send-data modulation pattern is fixed and the intensity modulation pattern is set at the first intensity modulation pattern, wherein the second optical intensity is measured when the intensity modulation pattern is changed to the second intensity modulation patten. ### Claim 16 (depends on 12) The non-transitory computer readable storage medium according to claim 12, wherein the intensity modulation pattern causes the second optical pulse train to repeat the reference intensity and the zero intensity every other double pulse by the optical pulse train repeatedly alternating between the reference intensity and the zero intensity every other pulse, the send-data modulation pattern includes a first send-data modulation pattern and a second send-data modulation pattern which alternate repeatedly, wherein the first send-data modulation pattern causes one pulse of the pulse pair to have zero intensity and the other pulse to have the reference intensity, wherein the second send-data modulation pattern causes the one pulse of the pulse pair to have the reference intensity and the other pulse to have the zero intensity, the c) comprises: deciding whether or not the pulse pair is the double pulse, by comparing a first optical intensity of the third optical pulse train with a second optical intensity of the third optical pulse train, wherein the first optical intensity is measured when one pattern of the intensity modulation pattern and the send-data modulation pattern is fixed and the other pattern is set at a predetermined pattern, wherein the second optical intensity is measured when the other pattern is inverted.