Project: Optical MIMO Communications: Propagation Channel Analysis and Communication Chain Performance

POSTDOC – 12 months

Start – as soon as possible

Place – IRCICA, USR 3380, Univ Lille – Lille, France

Required Skills: Either Signal Processing and Digital Communications, Matlab. MIMO techniques. Either Optics / Experimental Photonics

To apply send your CV, a letter of motivation and references to 


The evolution of telecoms makes it crucial to increase the maximum data transfer rates that can be transported by optical or wireless means. In the first case, the need is related to the announced saturation of the capacity of current monomode fibers [1].

IRCICA has a set of equipment dedicated to the generation and analysis of optical signals modulated in phase or amplitude. This Telecom chain is now operational for any single-mode fiber transmission project; a 2×2 MIMO processing that compensates for the interference of the two states of polarization is available. This configuration is also suitable for transmission tests on a special class of low multimode fiber, where all modes are non-degenerate, i.e., they do not exchange energy between them. Transmission tests on the active versions of such fibers (amplifying fibers) are in progress [2].

Recently, the bench has been completed to allow the generation and detection of two wavelengths simultaneously (512 Gbit / s or 2×256 Gbit / s). The chain is now able to generate and detect two completely independent signals, which will allow transmission tests to be extended to any class of low multimode fibers. The exchange of energy within each group means that to find the original information, 4×4 MIMO processing is necessary. Although MIMO processing is very widely used in wireless communication, it is not directly transferable to fiber communication and adaptation to the optical channel is essential [3].

Description of the project

The objective of the project is to develop a 4×4 MIMO processing for optical communications on low multimode fiber and to integrate this one with the Telecom channel. Two approaches can be envisaged according to the profile of the candidate: i) a “signal processing” approach using Matlab to do the MIMO processing in post-processing or ii) an “optical” approach using photonic components to make the MIMO treatment physical. This will characterize and model the transmission channel and optimize the signal processing to minimize the bit error rate. Extension to THz wireless communications may be considered, if time permits, the instruments used being the same. The tasks are:

  1. Characterization and modeling of the channel: in order to develop the right algorithms for retrieving information, it is necessary to characterize the properties of the multimode channel. If the optical properties of propagation are well controlled, the impact on baseband signals still needs to be studied, in particular nonlinearities and intermodal dispersion.
    1. Establishment of a channel characterization protocol.
    2. Measurements and analyzes.
  1. Transmission aspects: development of a 4×4 MIMO processing:
    1. Matlab development of MIMO 4×4
    2. Optimization of the execution time of the code (exploration of the most efficient / the most adapted estimation algorithms).
    3. Implementation for transmission on LP11a and LP11b modes of a circular core multimode fiber; or modes OAM + and OAM- of a multimode fiber with an annular core.
  1. Extend the study to 2×2 MIMO communications in pulsed THz with a target frequency of 300 GHz for very high speed broadband indoor applications.
  • Richardson et al., Nat. Photon. 7, 354 (2013).
  • Trinel et al., Opt. Fiber Technol., 35, 56-63, 2017.
  • Winzer et al., Opt. Express, 19, 16680 (2011).
  • Melati et al., Opt. Lett. 42(2) 342-345 (2017).

Ploschner et al. Nature Comm., 9, 529-535 (2015).