Correction and monitoring of laser phase noise in long-haul coherent optical multicarrier systems

Summary of the technology

Algorithm in the scope of carrier phase recovery for digital signal processors of multicarrier optical systems. It allows an unprecedented separate monitoring and compensation of the contributions of each of the two optical sources to phase noise.
This method presents considerable gains in links highly affected by fiber propagation effects related with lengthy transmission channels and allows the relaxation of the otherwise stringent requirements of laser optical sources.

Instituto de Telecomunicações
Instituto de Telecomunicações


Multi-Gigabit/Terabit data transmission across very long distance optical fiber networks, such as transcontinental communications, is a big challenge for the state-of-the-art technology. Coherent fiber optical communications have the unavoidable penalty associated with the quality of the two lasers at each end of the channel. These lasers are subject to stringent requirements in general, but even more so in ultra-long-haul links, where the fiber propagation highly emphasizes any non-ideality that the optical sources might have.

This invention presents a novel approach to collaborative laser phase noise correction in multicarrier transmission systems by being able to separate the contributions of each of the lasers in the system, thus being able to correct more accurately the affecting phase noise in each subcarrier. This is achieved through the usage of two reference subcarriers. In addition to phase noise correction, this invention allows for inline digital monitoring of the systems lasers independently, to identify and counteract on faulty lasers, being a huge advantage for modern day flexible transmission systems.


DIGITAL SIGNAL PROCESSORS OF COHERENT OPTICAL TRANSCEIVERS, used in very long distance optical fiber networks (e. g. transcontinental communications)


  • ENHANCED PERFORMANCE WITHOUT INCREASED COSTS: this technology enables an increased performance of the previously existing hardware without extra component costs.
  • INCREASED FLEXIBILITY OF SCM TRANSCEIVERS: this new solution allows increasing the number of digital sub-channels without compromising the transceiver performance.


TRL 5 - The method was experimentally validated in laboratory with real data, pointing to a viable commercial implementation.


Licensing agreement

Testing new applications

Joint further developments


Instituto deTelecomunicações seeks manufacturers of telecommunicationsequipments, which produce coherent opticaltranceivers.


Pending European patent application (EP4145723A1)


M. S. Neves, P. P. Monteiro and F. P.Guiomar, "Chromatic Dispersion-Aware Carrier-Phase Estimation for Digital Subcarrier Multiplexing Systems,"2020 European Conference on Optical Communications (ECOC), 2020, pp. 1-4,doi: 10.1109/ECOC48923.2020.9333181

M. S. Neves, P. P. Monteiro and F. P.Guiomar, "Enhanced Phase Estimation for Long-Haul Multi-Carrier Systems Using a Dual-Reference Subcarrier Approach," inJournal ofLightwave Technology, vol. 39, no. 9, pp. 2714-2724, 1 May1, 2021,doi: 10.1109/JLT.2021.3057680









Intellectual property status

  • Patent already applied for
  • Patent application number :Provisional Patent Application (priority date: 27-04-2020)
  • Patent already applied for
  • Patent application number :PCT/IB2021/053476

Attached documents

Related Keywords

  • Electronics, IT and Telecomms
  • Telecommunications, Networking
  • Broadband Technologies
  • Optical Networks and Systems
  • Optical Materials
  • Optics
  • Optical Technology related to measurements
  • Communications
  • Data Communications
  • Communications processors/network management
  • Other data communications
  • Electronics Related Market
  • Laser Related
  • Fibre Optics

About Instituto de Telecomunicações

Instituto de Telecomunicações (IT) is a private, not-for-profit organization, of public interest, a partnership of nine institutions with research and development in the field of Telecommunications

IT mission is to create and disseminate scientific knowledge in the field of telecommunications.

IT is actively involved in fundamental and applied research both at national and international levels. Simultaneously it is committed to foster higher education and training, by hosting and tutoring graduate and postgraduate students. it also plays its role towards public society with public awareness initiatives, knowledge transfer to industry, and by providing consulting services on a non-competing basis.

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