Talk:Orbital angular momentum multiplexing

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Comments[edit]

Calling OAM "hype" and saying it has "cooled down" is not a neutral point of view. Rdviii (talk) 11:33, 28 January 2016 (UTC)[reply]

After skimming this article: Edfors, O. and Johansson, A.J. (2012) "Is orbital angular momentum (OAM) based radio communication an unexploited area?", IEEE Transactions on Antennas and Propagation, Vol 60, Issue 2, pp 1126-1131. http://lup.lub.lu.se/luur/download?func=downloadFile&recordOId=2062936&fileOId=2339120 it appears there is an overlap between orbital angular momentum multiplexing and MIMO (multiple input multiple output) radio systems that, at a minimum, suggests these kinds of multiplexing gains will not be obtained. I am not an expert here, but the hype that has appeared in the press (like the cited BBC reference) may be hype. Broughturner (talk) 21:10, 27 June 2012 (UTC)[reply]

What a great paper! (Here's a DOI reference to it: Edfors, O.; Johansson, A. J. (2012). "Is Orbital Angular Momentum (OAM) Based Radio Communication an Unexploited Area?". IEEE Transactions on Antennas and Propagation. 60 (2): 1126. doi:10.1109/TAP.2011.2173142.)

Yes, it's true that the concepts of (classical) MIMO and (quantized) OAM blur into one another at a sufficiently small scale, and so OAM is unlikely to give any major extra gains for MIMO RF systems (although the OAM conceptualization may help designers design antennae which may help them implement MIMO more efficiently).

The really interesting case is the use of OAM in optics, where thinking of OAM in terms of the quantum model is much simpler and more useful than thinking of it as a classical effect: if the barriers to use in fiber optics can be overcome, in a similar way to the way that they have been for polarization multiplexing, OAM could easily result in a 10-fold increase in the bandwidth capacity of a single fiber strand, when used in addition to the current state of the art using WDM and polarization-multiplexed modulation.

Which is handy, because we will probably need it soon (next 5 years or so), to progress towards practical low-cost wide-area 1000 gigabit Ethernet and beyond. -- The Anome (talk) 09:53, 3 July 2012 (UTC)[reply]

Update: I've now integrated the conclusions of the Edfors and Johnasson paper into the article. -- The Anome (talk) 10:59, 3 July 2012 (UTC)[reply]

Noticed this today from AAAS: "Terabit-Scale Orbital Angular Momentum Mode Division Multiplexing in Fibers" - Science 28 June 2013: Vol. 340 no. 6140 pp. 1545-1548 DOI: 10.1126/science.1237861 — Preceding unsigned comment added by Paulthedesertrat (talk • contribs) 15:40, 31 July 2013 (UTC)[reply]

I've now added that to the article. Thanks. -- Rangeweedle (talk) 22:24, 16 December 2013 (UTC)[reply]

The hype around OAM is (was) nothing but a scientific hoax. We can forget about OAM, and move on. — Preceding unsigned comment added by 85.224.153.235 (talk) 19:59, 14 June 2014 (UTC)[reply]

I don't think there's anything to suggest that it's anything of the sort. The concept of multiple propagation modes down a single fiber, particularly if that fiber is made in such a way as to encourage the formation of vortex-like modes, seems entirely reasonable, and seems to have been demonstrated in real experiments. Whether it makes economic and practical sense to try to exploit it at the moment, given the current success of extending WDM, coherent modulation, polarization multiplexing, signal processing and channel coding techniques further and further, is an entirely different matter. I don't doubt that OAM (or some other equivalent single-fibre multimode MIMO technique) will eventually be put into practice, but only once commercializing it is more cost-effective than pushing these other techniques further. -- The Anome (talk) 13:22, 24 November 2015 (UTC)[reply]

Anome is 100% correct: not only can we demonstrate OAM modes in an experimental setting, they actually have a LOT of interesting fiber applications. Sadly communications is probably not one, at least for a long time. The specialty fibers we use to get >1km stable propagation results with L of up to 7 are absurdly expensive (thousands of dollars per km) relative to cheap SMF (tens of dollars per km), and have worse performance in many ways because of being multi-moded and the difficulties of making their unusual structure. That does not mean that there are not a lot of people interested in the development of the field, and it is developing. That's the fun of the bleeding edge. BeardSenpai (talk) 20:51, 24 November 2015 (UTC)[reply]