DOFI has world-leading expertise within few-mode fibers and was started to bring few-mode fiber technologies from the current research state into actual commercial use.
The activities mainly focus on mode converters based on photonic lanterns and long-period gratings and their application for communication and sensing.
From 2018 to 2021 DOFI was part of the INCOM research collaboration on Innovative Solutions for Next Generation Communications Infrastructure funded by Innovation Fund Denmark. The DOFI part focused together with DTU Electro on developing few-mode technologies for future intra-datacenter communication.
From 2021 to 2025 DOFI is part of the GO-SENS project aiming at developing the next generation of distributed optical fiber sensors for real-time monitoring of the well-being of high-voltage power cables. This project (0224-00074A) is also funded by Innovation Fund Denmark.
From 2023 to 2026 DOFI is part of the GreenCom project funded by Innovation Fund Denmark on innovative solutions for the next generation of green communications infrastructures. DOFI will work together with DTU Electro in WP4 - Task 2 on photonic lanterns for increased capacity and reduced electrical power consumption of data center interconnects.
DOFI has a close collaboration with DTU Electro, including the
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List of publications 2017
F. Parmigiani, Y. Jung, P. Horak, L. Grüner-Nielsen, T. Geisler, P. Petropoulos, D. Richardson; C- to L- band Wavelength Conversion Enabled by Parametric Processes in a Few Mode Fiber; Proceedings of OFC, paper, Th1F.4; 2017
M. Lillieholm, P. Guan, M. S. Møller-Kristensen, M. Galili, L. Grüner-Nielsen, and L. K. Oxenløwe; Continuous-Wave-based Characterization of Nonlinear Fibers for Four-Wave Mixing using Chirped Pump Pulses; Proceedings of CLEO, paper STh4K.4; 2017
F. Parmigiani, Y. Jung, L. Grüner-Nielsen, T. Geisler, P. Petropoulos, D. Richardson; MIMO-less Space Division Multiplexing Transmission over 1 km Elliptical Core Few Mode Fiber; Upgraded Invited; Proceedings of CLEO, paper SW1I.1; 2017
M. Lillieholm, P. Guan, M. Galili, M. S. Møller-Kristensen, L. Grüner-Nielsen, And L. K. Oxenløwe; Optimization and characterization of highly nonlinear fiber for broadband optical time lens applications; Optics Express, Vol. 25, No. 11, pp. 12566-12580 ; 2017
Alma Fernandez, Marco Andreana, Lars Grüner-Nielsen, Thomas Andersen, Martin Distel,
Lingxiao Zhu, Andrius Baltuska, Rainer Leitgeb, Kim Jespersen, and Aart Verhoef; Optimizing the Fluorescent Signal for In-Vivo Nonlinear Imaging in a Completely
All-Fibered Ytterbium Chirped Pulse Amplifier; Proceedings of CLEO Europe, paper JS ECBO/CLEO.2; 2017
A. Fernández, L. Grüner-Nielsen, M. Distel, T. Andersen, M. Andreana, M. Stadler, S. Kirchberger, C. Sturtzel, L. Zhu, W. Kautek, R. Leitgeb, A. Baltuska, K. Jespersen, A. Verhoef; Optimizing pulse compressibility in completely all-fibered ytterbium chirped pulse amplifiers for in vivo two photon laser scanning microscopy; Biomedical Optics Express, Vol. 8, No. 8, pp. 3526-3537; 2017
Lars Grüner-Nielsen, and Søren Herstrøm; Brillouin Gain Spectra of Few Mode Fibres; Proceedings of ECOC, Paper P1.SC1.1; 2017
M. Lillieholm, B. Corcoran, M. Galili, L. Grüner-Nielsen, L. K. Oxenløwe and A. J. Lowery; Characterization of Advanced Modulation Formats for Spectral Magnification based on Four-Wave Mixing in Nonlinear Fibre; Proceedings of ECOC, Paper P1.SC4.65; 2017
F. Parmigiani, M. Guasoni, O. Anjum, P. Horak, Y. Jung, L. Grüner-Nielsen, P. Petropoulos, D. J. Richardson; Polarization Insensitive Wavelength Conversion in a Few Mode Fibre; Proceedings of ECOC, Paper W.2.F.2; 2017
F. Parmigiani, Y. Jung, L. Grüner-Nielsen, T. Geisler, P. Petropoulos, D. J. Richardson; Elliptical Core Few Mode Fibers for Multiple-Input Multiple Output-free Space Division Multiplexing Transmission; Photonics Technology Letters, Vol. 29, No. 21, pp. 1764-1767; 2017
F. Parmigiani, P. Horak, Y. Jung, L. Grüner-Nielsen, T. Geisler, P. Petropoulos, D. J. Richardson; Flexible All-Optical Mode and Wavelength Converter based on Parametric Processes in a Three-Mode Fiber; Optics Express, Vol. 25, No. 26, pp. ;2017
List of publications 2018
Neethu Mariam Mathew, Lars Grüner-Nielsen, Mario A Usuga Castaneda, Karsten Rottwitt; A Novel Fabrication Method for Photonic Lanterns; Proceedings of OFC, paper M4D.4; 2018
Neethu M. Mathew, Erik N. Christensen, Lars Grüner-Nielsen, and Karsten Rottwitt; Improved SBS limited parametric conversion by use of few-mode fibers; Proceedings of ECOC, Paper We2.1; 2018
Neethu M. Mathew, Lars Grüner-Nielsen, Mario A. U. Castaneda, Michael Galili, and Karsten Rottwitt; Mode-Group Selective Air-Clad Photonic Lantern; Proceedings of Frontiers in Optics, Paper FTu5B; 2018
List of publications 2019
Lars Grüner-Nielsen, Neethu Mariam Mathew, and Karsten Rottwitt; Direct Measurement of Polarization Dependency of Mode Conversion in a Long Period Grating; Proceedings of OFC, paper Th2A.15.4; 2019
Neethu Mariam Mathew, Lars Grüner-Nielsen, Michael Galili, Mads Lillieholm, Mario A. Usuga Castaneda, Karsten Rottwitt; Polarization Dependence of Mode-Group Selective Air-Clad Photonic Lantern; Proceedings of OFC, paper Th3D.6; 2019
Neethu Mariam Mathew, Jesper Bjerge Christensen, Lars Grüner-Nielsen, Michael Galili, Karsten Rottwitt; Air-cladded mode-group selective photonic lanterns for mode-division multiplexing; Optics Express, Vol. 27, No. 9. pp. 13329-13343; 2019
Lars Grüner-Nielsen, Neethu Mariam Mathew, and Karsten Rottwitt; Characterization of Few Mode Fibers and Devices; Invited Paper; Optical Fiber Technology; Vol. 52; 2019
List of publications 2020
Neethu Mariam Mathew, Lars Grüner-Nielsen, Michael Galili, Mads Lillieholm, and Karsten Rottwitt; Cross Talk and Interference in MIMO less Few Mode Transmission Systems; Proceedings of CLEO, paper JW2E.24; 2020
Neethu Mariam Mathew, Lars Grüner-Nielsen, Michael Galili, Mads Lillieholm, and Karsten Rottwitt; MDM transmission using air-clad photonic lanterns; Photonics Technology Letters, Vol. 32, No. 17, pp. 1049-1052; 2020
Lars Grüner-Nielsen, Neethu Mariam Mathew, Mads Lillieholm, Michael Galili, and Karsten Rottwitt; Modeling of MIMO less Mode Division Multiplexed Systems; Photonics Technology Letters, Vol. 32, No. 18, pp. 1191-1194; 2020
List of publications 2021
Parisah Akrami, Lars Grüner-Nielsen, Lars Søgaard Rishøj, and Karsten Rottwitt; Fabrication of heat induced long period gratings for mode conversion in few mode fibers; Proc. SPIE 11713; 2021
Lars Grüner-Nielsen, Neethu Mariam Mathew, and Karsten Rottwitt ; Characterization of Few Mode Fiber Components and Connected Systems; Editors’ Pick, Optics Express, Vol. 29, No. 2, pp. 1140-1146; 2021
Lars Grüner-Nielsen, Neethu Mariam Mathew, Magnus Hornhaver Nymann, Mads Lillieholm, Michael Galili, and Karsten Rottwitt; Mode Division Multiplexing on Standard 50/125 mm Multi Mode Fiber using Photonic Lanterns; Proceedings of OFC, paper W6A.41; 2021
Dipankar Sen, Anton Classen, Alma Fernández, Lars Grünernielsen, Holly C. Gibbs, Shahriar Esmaeili, Philip Hemmer, Andrius Baltuska, Alexei V. Sokolov, Marlan O. Scully, Rainer A. Leitgeb, and Aart J. Verhoef; Extended focal Depth Fourier Domain Optical Coherence Microscopy with Bessel-Beam – LP02 mode – from a Higher Order Mode Fiber; Biomedical Optics Express, Vol. 12, No. 12, pp. 7327-7337; 2021
List of publications 2022
Neethu Mariam Mathew, Lars Grüner-Nielsen, Zepeng Wang, Lars Søgaard Rishøj, and Karsten Rottwitt; Broadband air clad LP02 mode convertor using tapered mode transition; Optics Letters, Vol. 47, No. 1, pp. 38-41; 2022
Metodi P. Yankov, Francesco Da Ros, Søren Forchhammer, and Lars Grüner-Nielsen; Capacity and Achievable Rates of Fading Few-mode MIMO IM/DD Optical Fiber Channels; ICC22; 2022
João M. B. Pereira, Lars Grüner-Nielsen, Karsten Rottwitt, Graham Town, Fredrik Laurell, and Walter Margulis; Electrooptic control of the modal distribution in a silicate fiber; Optics Express, Vol. 30, No. 8, pp. 12474-12483; 2022
Dipankar Sen, Anton Classen, Lars Grüner-Nielsen, Holly Gibbs, Shahriar Esmaeili, Philip Hemmer, Andrius Baltuska, Alexei Sokolov, Rainer Leitgeb, Alma Fernández, Aart Verhoef; Implementation of Bessel-Like LP02 Mode From Higher Order Mode (HOM) Fiber to Extend the Depth of Focus in Fourier Domain Optical Coherence Microscopy (FD-OCM); CLEO, paper AM5I.5; 2022
Anton Classen, Dipankar Sen, Lars Grüner-Nielsen, Holly Gibbs, Shahriar Esmaeili, Philip Hemmer, Andrius Baltuska, Alexei Sokolov, Rainer Leitgeb, Alma Fernández, Aart Verhoef; Modeling the Image Formation Process in Fourier Domain Optical Coherence Microscopy for a Bessel-Like LP02 Mode From a Higher Order Mode Fiber; CLEO, paper JW3A.3; 2022
João Manoel Barbosa Pereira, Lars Grüner-Nielsen, Karsten Rottwitt, Fredrik Laurell, Walter Margulis; Electrooptic Intermodal Interference in Silicate Fibers with Internal Electrodes; CLEO, paper Stu5P.1; 2022
Neethu Mariam Mathew, Lars Grüner-Nielsen, Michael Galili, Karsten Rottwitt; Air clad Photonic Lanterns; Invited paper; IEEE Summer Topicals, paper WC3.2; 2022
Neethu Mariam Mathew, Lars Grüner-Nielsen, Mads Lillieholm, Michael Galili, Karsten Rottwitt; Air-clad photonic lanterns: Fabrication and applications; Journal of Optics, Vol. 24, No. 5 p. 054011; 2022
Lars Grüner-Nielsen, Michael Stübert Berger, Mads Nielsen, Neethu Mariam Mathew, and Karsten Rottwitt; A Converter for Transmission with Singlemode Performance on OM2/3/4/5 Multimode Fibers; Photonics Technology Letters, Vol. 34, No. 11, pp. 571-574; 2022
Mads Holmark Vandborg, Neethu Mariam Mathew, Jesper Bjerge Christensen, Lars Søgaard Rishøj, Lars Grüner-Nielsen, Karsten Rottwitt; Simulations and Measurements of Spontaneously Initiated Brillouin Scattering in Optical Fibers; ECOC, paper Tu5.2; 2022
List of publications 2023
Lars Grüner-Nielsen, Neethu Mariam Mathew, Michael Galili, Lars Søgaard Rishøj, and Karsten Rottwitt; Photonic-Lantern-Based MDM Devices; Invited paper; OFC; paper M1B.5; 2023
Mads Holmark Vandborg, Lars Grüner-Nielsen, Neethu Mariam Mathew, Lars Søgaard Rishøj, Thorben Jostmeier, Benjamin Marx, and Karsten Rottwitt; Intermodal Brillouin Gain Spectra in Few Mode Optical Fibers; CLEO, paper SM4L.6; 2023
Zepeng Wang, Mads Holmark Vandborg, Tomin Joy, Neethu Mariam Mathew, Lars Grüner-Nielsen, Lars Søgaard Rishøj, Jesper Bjerge Christensen, Thorben Jostmeier, Benjamin Marx, Wieland Hill, and Karsten Rottwitt; Mitigating probe pulse deformation in Raman amplification in OTDR fiber sensing systems; Optics Express, Vol. 31, No. 7, pp. 11457-11470; 2023
Denis Bolotov, Lars Grüner-Nielsen, Karsten Rottwitt, and Lars Søgaard Rishøj; Efficient All-Fiber Broadband Frequency Conversion via Intermodal Bragg Scattering; IEEE Summer Topical Meeting, paper WB1.3; 2023
Ninik Irawati, Lars Grüner-Nielsen,, Lars Søgaard Rishøj, and Karsten Rottwitt; Strain and Temperature Sensor Using Few-mode Fiber, Designing Guidelines and Results; Optical Fiber Technology; Vol. 80, p 103465; 2023
Mads Vandborg, Neethu Mathew, Jesper Christensen, Tomin Joy, M. Ali Allousch, Benjamin Marx, Thorben Jostmeier, Lars Grüner-Nielsen, Lars Rishøj, and Karsten Rottwitt; Modelling the Brillouin spectrum in Raman amplifier assisted Brillouin OTDR; OFS, paper Tu3.19; 2023
List of publications 2024
Metodi Plamenov Yankov, Francesco Da Ros, Søren Forchhammer, Lars Grüner-Nielsen; Channel fading-robust pre-coders for low complexity few-mode IM/DD short reach fiber communications; Journal of Lightwave Technology; Vol. 42, No. 5, pp. 1434-1442; 2024
Neethu Mariam Mathew, Mads Holmark Vandborg, Jesper Bjerge Christensen, Zepeng Wang, Lars Grüner-Nielsen, Lars Søgaard Rishøj, Benjamin Marx, M. Ali Allousch, Tommy Geisler, Mikael Lassen, and Karsten Rottwitt; Repeaterless Brillouin OTDR Sensing over 250 km using Erbium doped Fiber Amplifier, OFC, paper M2K; 2024
Rodrigo Amorim, Kasper Alexander, Lars Grüner-Nielsen, and Karsten Rottwitt; Spatial Mode Conversion of Single Photons Using Long-Period Grating; CLEO-Pacific; 2024
Mads Vandborg, Neethu Mathew, Jesper Christensen, Tomin Joy, M. Ali Allousch, Benjamin Marx, Lars Grüner-Nielsen, Lars Rishøj, and Karsten Rottwitti, ”Modeling the Brillouin spectrum in Raman amplifier-assisted Brillouin OTDR”, Journal of Lightwave Technology; 2024