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Mode Division Multiplexing

Acronym: MDM

Definition: a multiplexing technique for data transmission in fibers, where different fiber modes are used for different channels

Category: lightwave communications

How to cite the article; suggest additional literature


Mode division multiplexing (MDM) is a technique which is applied in some modern systems for optical fiber communications for increasing the data capacity. Essentially, the idea is using different guided modes of a multimode fiber for different transmission channels.

Components for MDM

The following types of components are typically used for mode division multiplexing:

  • Typically, the used multimode fibers have a relatively small number of guided modes and are thus called few-mode fibers. They may in principle be step-index fibers, but often one uses graded-index fibers optimized for minimum differential modal group delay (DMGD), because that allows the use of simpler receiver technology.
  • Certain kinds of spatial multiplexers (SMUX) are required for (a) injecting signals from multiple single-mode fibers into the core of a few-mode fiber and (b) for separating the signals after transmission, sending them to different photodetectors. Different kinds of spatial multiplexers have been developed. Some of them are based on certain phase plates, others on photonic laterns.
  • For maintaining sufficiently high signal powers over large distances, there are special fiber amplifiers (mostly erbium-doped fiber amplifiers = EDFAs) for few-mode fibers, which are optimized for minimum variations of modal gain.

Because there is always a substantial cross-talk between the different channels, receivers need to be equipped with special electronics based on MIMO techniques (multiple inputs / multiple outputs), similar to those which are already widely used for wireless data transmission, for example for WLAN.

The requirements on fusion splicers are more demanding than for splicing ordinary multimode fibers, since one needs to minimize mode -dependent losses.

Combination with Other Multiplexing Techniques

Mode division multiplexing can be combined with other techniques like wavelength division multiplexing. It is expected to become important for satisfying the first one rising demand of data transmission capacities.

For a more detailed discussion, including the comparison with other techniques, see the article on space division multiplexing.


The RP Photonics Buyer's Guide contains 2 suppliers for mode division multiplexing devices.


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[9]V. A. J. M. Sleiffer et al., “73.7 Tb/s (96 × 3 × 256-Gb/s) mode-division-multiplexed DP-16QAM transmission with inline MM-EDFA”, Opt. Express 20 (26), B428 (2012)
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[11]T. Hayashi et al., “Physical interpretation of intercore crosstalk in multicore fiber: Effects of macrobend, structure fluctuation, and microbend”, Opt. Express 21 (5), 5401 (2013)
[12]P. Sillard, M. Bigot-Astruc and D. Molin, “Few-mode fibers for mode-division-multiplexed systems”, J. Lightwave Technol. 32 (16), 2824 (2014)
[13]P. J. Winzer, “Making spatial multiplexing a reality”, Nat. Photonics 8 (5), 345 (2014)
[14]R. G. H. van Uden et al., “Ultra-high-density spatial division multiplexing with a few-mode multicore fibre”, Nature Photonics 8, 865 (2014)
[15]Y. Jung et al., “Cladding pumped few-mode EDFA for mode division multiplexed transmission”, Opt. Express 22 (23), 29008 (2014)
[16]G. Lopez-Galmiche et al., “Few-mode erbium-doped fiber amplifier with photonic lantern for pump spatial mode control”, Opt. Lett. 41 (11), 2588 (2016)

(Suggest additional literature!)

See also: space division multiplexing, few-mode fibers, graded-index fibers, fiber amplifiers
and other articles in the category lightwave communications


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