# US 8,571,419 B2 · Method and system for flexible optical signal aggregation and transmission > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,571,419 B2 - Document ID: US8571419B2 - Status: Granted - Kind: B2 - Application number: 13/224,114 - Filed: 2011-09-01 - Published: 2013-03-07 - Granted: 2013-10-29 - Earliest claimed: 2011-09-01 - Assignees: Fujitsu Limited - Applicants: Martin Bouda - Inventors: Martin Bouda - Web page: https://patentgrep.com/patent/US8571419B2 ## CPC - H04J 14/0212: {using optical switches or wavelength selective switches [WSS]} - H04J 14/0256: {at the optical channel layer} - H04J 14/0282: {WDM tree architectures} - H04J 14/06: Polarisation multiplex systems - H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S) ## Abstract In accordance with some embodiments of the present disclosure, a method for spectrally spacing carrier waves comprises determining a frequency offset between a first frequency of a first optical carrier wave and a second frequency of a second optical carrier wave. The method further comprises adjusting the second frequency of the second optical carrier wave according to the frequency offset. The method additionally comprises combining a first optical signal associated with the first carrier wave and a second optical signal associated with he second carrier wave into a multi-frequency signal. ## Claims ### Claim 1 A system comprising: a coherent optical receiver configured to determine a frequency offset between a first frequency of a first optical carrier wave and a second frequency of a second optical carrier wave, wherein the first optical carrier wave is modulated with first information to form a first optical signal and the coherent optical receiver is configured to demodulate the first information associated with the first optical signal; a tunable optical transmitter comprising a tunable laser configured to generate the second optical carrier wave at the second frequency and coupled to the coherent optical receiver such that the coherent optical receiver receives the second optical carrier wave from the tunable laser; a control unit coupled to the coherent optical receiver and the tunable optical transmitter and configured to receive the frequency offset from the coherent optical receiver and adjust the second frequency of the tunable laser according to the frequency offset; and a signal combiner circuit coupled to the tunable optical transmitter and configured to combine the first optical signal with a second optical signal generated by the tunable optical transmitter by modulating second information on the second optical carrier wave. ### Claim 2 (depends on 1) The system of claim 1, wherein the control unit is further configured to compare a target offset with the frequency offset received from the coherent optical receiver and adjust the second frequency such that the determined frequency offset is substantially equal to the target offset. ### Claim 3 (depends on 1) The system of claim 1, further comprising a frequency translator coupled between the coherent optical receiver and the tunable laser, the frequency translator configured to shift the second frequency of the second optical carrier wave before the second optical carrier wave is received by the coherent optical receiver from the tunable laser. ### Claim 4 (depends on 3) The system of claim 3, wherein the control unit is further configured to adjust the second frequency such that the determined frequency offset combined with the shift in the second frequency is substantially equal to the target offset. ### Claim 5 (depends on 3) The system of claim 3, further comprising: a plurality of tunable optical transmitter s each comprising a tunable laser configured to generate an optical carrier wave; and an optical switch coupled between the plurality of tunable lasers and the coherent optical receiver, the optical switch configured to select one of the plurality of tunable lasers to provide the second optical carrier wave to the coherent optical receiver. ### Claim 6 (depends on 1) The system of claim 1, further comprising a frequency comb generator coupled between the coherent optical receiver and the tunable laser, the frequency comb generator configured to receive the second optical carrier wave from the tunable laser and create a number of distinct frequencies from the second optical carrier wave before the second optical carrier wave is received by the coherent optical receiver. ### Claim 7 (depends on 1) The system of claim 1, wherein the signal combiner circuit includes a wavelength selective switch (WSS). ### Claim 8 (depends on 1) The system of claim 1, wherein the first optical signal has a first phase and the second optical signal has a second phase, the system further comprising a signal controller coupled between the tunable optical transmitter and the signal combiner circuit and configured to adjust the second phase according to the first phase. ### Claim 9 (depends on 1) The system of claim 1, wherein the first optical signal has a first polarization and the second optical signal has a second polarization, the system further comprising a signal controller coupled between the tunable optical transmitter and the signal combiner circuit and configured to adjust the second polarization according to the first polarization. ### Claim 10 A method for spectrally spacing carrier waves comprising: receiving a first optical signal comprising a first optical carrier wave modulated with first information; demodulating the first information associated with the first optical signal; determining a frequency offset between a first frequency of the first optical carrier wave and a second frequency of a second optical carrier wave; adjusting the second frequency according to the frequency offset; and combining the first optical signal and a second optical signal into a multi-frequency signal, the second optical signal comprising the second optical carrier wave modulated with second information. ### Claim 11 (depends on 10) The method of claim 10, further comprising: comparing a target frequency offset with the frequency offset; and adjusting the second frequency such that the determined frequency offset is substantially equal to the target frequency offset. ### Claim 12 (depends on 10) The method of claim 10, further comprising shifting the second frequency before determining the frequency offset. ### Claim 13 (depends on 12) The method of claim 12, further comprising adjusting the second frequency such that the determined frequency offset combined with the shift in the second frequency is substantially equal to the target offset. ### Claim 14 (depends on 10) The method of claim 10, further comprising optically selecting one out of a multitude of tunable lasers to source the second optical carrier wave. ### Claim 15 (depends on 10) The method of claim 10, further comprising adjusting a second polarization of the second optical carrier wave according to a first polarization of the first optical carrier wave. ### Claim 16 (depends on 10) The method of claim 10, further comprising adjusting a second phase of the second optical carrier wave according to a first phase of the first optical carrier wave.