Periodic Reporting for period 2 - WON (Wideband Optical Networks)
Reporting period: 2021-01-01 to 2023-06-30
WON is a research and training programme funded by the European Commission under the MSCA GA 814276. WON consists of internationally leading teams from industry and academia who provide training to 14 Early Stage Researchers in the emerging field of wideband optical networks.
In an era of exceptional internet expansion, accelerated by the global impact of the COVID-19 pandemic, advancements in the field of optical networks are crucial. In this context, solutions identified in WON enable fuller exploitation of the information-carrying capacity of standard optical fibres to sustain internet traffic growth and to overcome a possible capacity crunch. A special focus of the research was to develop physical layer aware planning tools for accurate estimation of overall system performance and prediction of network capacity. WON provides cost effective and realistic solutions to current bandwidth saturation, which is already limiting the capacity of deployed networks.
The WON project focuses on a pivotal concern – the full utilization of the optical fibre already globally deployed by network operators. This endeavour takes on profound significance, answering the imperative call for efficient data transmission, uninterrupted connectivity, and dependable information exchange, all of which lie at the core of today's interconnected world, while simultaneously supporting a sustainable society and a greener future.
The project has achieved its main goals and proven to be a successful collaboration.
In an era of exceptional internet expansion, accelerated by the global impact of the COVID-19 pandemic, advancements in the field of optical networks are crucial. In this context, solutions identified in WON enable fuller exploitation of the information-carrying capacity of standard optical fibres to sustain internet traffic growth and to overcome a possible capacity crunch. A special focus of the research was to develop physical layer aware planning tools for accurate estimation of overall system performance and prediction of network capacity. WON provides cost effective and realistic solutions to current bandwidth saturation, which is already limiting the capacity of deployed networks.
The WON project focuses on a pivotal concern – the full utilization of the optical fibre already globally deployed by network operators. This endeavour takes on profound significance, answering the imperative call for efficient data transmission, uninterrupted connectivity, and dependable information exchange, all of which lie at the core of today's interconnected world, while simultaneously supporting a sustainable society and a greener future.
The project has achieved its main goals and proven to be a successful collaboration.
WON has produced numerous research results which are available in deliverables and the extensive list of publications. The most important results include:
• The main limiting transmission effects in wideband systems have been identified, and a model for nonlinear interference (NLI) generation within them has been derived and assessed.
• Machine learning has been used to predict the best operating points in terms of atness, relative intensity noise, free spectral range and driving voltages for lasers and modulators focusing on multiband transmission. Machine learning has also been evaluated for the compensation of degradations induced by amplified spontaneous emission noise.
• Developments in digital pre-compensation techniques for wideband networks have been addressed, focusing on the design of optical transceivers based on Indium Phosphide (InP) modulators including an autonomous identification and pre-distortion scheme using cognitive algorithms and the use of C-band transceivers in multi-band systems, by characterizing, monitoring and mitigating impairments of these devices working out-of-band.
• In the area of analytical transmission modelling for wideband systems, activities were conducted by blending theoretical advancements, split-step simulations, and collaboration with the GNPy project of the Telecom Infra Project. Model assessment for multi-channel effects has been conducted, results addressing single channel effects have been published in one project paper, and models applied and tested against experimental data.
• DSP-based monitoring for amplifier gain profile estimation and failure detection in a C+L spectral scenario was investigated.
• The work on wideband filters resulted in an extensive set of simulations of filters and wavelength (de-) multiplexers. A novel photonic integrated 40-channels 100 GHz spaced Mux/Demux was demonstrated, based on the cascaded one 1×8 100 GHz PEG and eight 1×5 800 GHz PEGs designed and fabricated on 3-µm SOI platform.
• A lossless semiconductor optical amplifier (SOA) based multi-band Optical Add-Drop Multiplexer was presented, operating in the O, S, C and L-bands suitable for the transparent and programmable metro-access networks. A wideband, nanosecond switching and low polarization sensitive 1×2 electro-optic Mach-Zhender Interferometer switch on a 3-μm silicon platform was fabricated and demonstrated.
• The wideband transceiver concept and specifications were developed, focused on basic transceiver building blocks, including novel techniques for impairment estimation and determined target specifications for each building block.
• Progress was made in developing the InP-based coherent transmitter building blocks via extensive experimental work and simulations from 1260nm to 1568nm, whilst measurement were restricted to the C-band and O-band, due to the lack of an E-band laser source.
• A narrow-linewidth widely tunable III-V-on-Si laser was demonstrated with 110nm tunability realized using micro-transfer printing technology. This work was based on the integration of pre-fabricated III-V SOAs onto IMEC’s SiPh platform using UGent’s micro-transfer printing technology.
• A novel design of transfer-printing compatible high saturation power semiconductor optical amplifiers (SOA) was provided, as a power booster for the previously mentioned lasers without exhibiting saturation at high powers.
WON organised numerous training events, published 68 peer-reviewed journal and conference papers, the ESRs delivered 64 talks at world-leading conferences, and WON organised dedicated workshops at major scientific conferences, such as the Special Event at ECOC 2021 and the UWB topic area at IEEE Photonics Society Summer Topicals 2021 and 2022. 12 ESRs have enrolled in PhD programs, 4 ESRs defended their PhD theses, and those remaining are due by the end of 2023. After WON, 5 ESRs continued their careers at leading industrial companies, e.g. NKT Photonics (DK), ADVA (DE), ASML (NL), Deutsche Telekom (DE), and Infinera (PT). Meanwhile, some ESRs have chosen an academic path, with roles at institutions such as UCL (UK), Aston (UK) etc.
• The main limiting transmission effects in wideband systems have been identified, and a model for nonlinear interference (NLI) generation within them has been derived and assessed.
• Machine learning has been used to predict the best operating points in terms of atness, relative intensity noise, free spectral range and driving voltages for lasers and modulators focusing on multiband transmission. Machine learning has also been evaluated for the compensation of degradations induced by amplified spontaneous emission noise.
• Developments in digital pre-compensation techniques for wideband networks have been addressed, focusing on the design of optical transceivers based on Indium Phosphide (InP) modulators including an autonomous identification and pre-distortion scheme using cognitive algorithms and the use of C-band transceivers in multi-band systems, by characterizing, monitoring and mitigating impairments of these devices working out-of-band.
• In the area of analytical transmission modelling for wideband systems, activities were conducted by blending theoretical advancements, split-step simulations, and collaboration with the GNPy project of the Telecom Infra Project. Model assessment for multi-channel effects has been conducted, results addressing single channel effects have been published in one project paper, and models applied and tested against experimental data.
• DSP-based monitoring for amplifier gain profile estimation and failure detection in a C+L spectral scenario was investigated.
• The work on wideband filters resulted in an extensive set of simulations of filters and wavelength (de-) multiplexers. A novel photonic integrated 40-channels 100 GHz spaced Mux/Demux was demonstrated, based on the cascaded one 1×8 100 GHz PEG and eight 1×5 800 GHz PEGs designed and fabricated on 3-µm SOI platform.
• A lossless semiconductor optical amplifier (SOA) based multi-band Optical Add-Drop Multiplexer was presented, operating in the O, S, C and L-bands suitable for the transparent and programmable metro-access networks. A wideband, nanosecond switching and low polarization sensitive 1×2 electro-optic Mach-Zhender Interferometer switch on a 3-μm silicon platform was fabricated and demonstrated.
• The wideband transceiver concept and specifications were developed, focused on basic transceiver building blocks, including novel techniques for impairment estimation and determined target specifications for each building block.
• Progress was made in developing the InP-based coherent transmitter building blocks via extensive experimental work and simulations from 1260nm to 1568nm, whilst measurement were restricted to the C-band and O-band, due to the lack of an E-band laser source.
• A narrow-linewidth widely tunable III-V-on-Si laser was demonstrated with 110nm tunability realized using micro-transfer printing technology. This work was based on the integration of pre-fabricated III-V SOAs onto IMEC’s SiPh platform using UGent’s micro-transfer printing technology.
• A novel design of transfer-printing compatible high saturation power semiconductor optical amplifiers (SOA) was provided, as a power booster for the previously mentioned lasers without exhibiting saturation at high powers.
WON organised numerous training events, published 68 peer-reviewed journal and conference papers, the ESRs delivered 64 talks at world-leading conferences, and WON organised dedicated workshops at major scientific conferences, such as the Special Event at ECOC 2021 and the UWB topic area at IEEE Photonics Society Summer Topicals 2021 and 2022. 12 ESRs have enrolled in PhD programs, 4 ESRs defended their PhD theses, and those remaining are due by the end of 2023. After WON, 5 ESRs continued their careers at leading industrial companies, e.g. NKT Photonics (DK), ADVA (DE), ASML (NL), Deutsche Telekom (DE), and Infinera (PT). Meanwhile, some ESRs have chosen an academic path, with roles at institutions such as UCL (UK), Aston (UK) etc.
The WON project has confirmed the potential viability of wideband systems operating beyond the C-band to offer an economically attractive and green multi-band approach to deliver optical network capacity increase via presently unused spectral bands. Important advances beyond the pre-existing state-of-the-art have been made in accurate system modelling and physical layer-aware planning tools to quantitatively demonstrate these benefits via techno-economic analyses of networks. Moreover, ground-breaking results have been delivered in key wideband photonic components and sub-systems, including transceivers, amplifiers, and filters, and in network management, monitoring and control for wideband operation, in some cases utilising novel DSP and ML techniques.
During the WON project, there has been strong growth in global research interest in all aspects of wideband optical networks, as evidenced by the volume of journal publications, strong citations for WON papers (including 200 for a joint WON consortium paper), and continued organisation of relevant workshops at major conferences. Furthermore, there is a clear trend towards supporting wideband transmission in industry, with the recent emergence of C+L-band systems for terrestrial networks and the first deployment of a C+L-band transoceanic submarine system. Finally, recent transmission experiments have improved the highest data rate achieved in prototype S+C+L-band systems up to 256.4Tbit/s over a bandwidth of 157nm in 2022, from 115Tbit/s over 100nm in 2017.
During the WON project, there has been strong growth in global research interest in all aspects of wideband optical networks, as evidenced by the volume of journal publications, strong citations for WON papers (including 200 for a joint WON consortium paper), and continued organisation of relevant workshops at major conferences. Furthermore, there is a clear trend towards supporting wideband transmission in industry, with the recent emergence of C+L-band systems for terrestrial networks and the first deployment of a C+L-band transoceanic submarine system. Finally, recent transmission experiments have improved the highest data rate achieved in prototype S+C+L-band systems up to 256.4Tbit/s over a bandwidth of 157nm in 2022, from 115Tbit/s over 100nm in 2017.