On 05/04/2012 10:03 PM, Erik Basilier wrote: > * The claim was not just that you can have two independent communications > (as possible by means of circular polarization), but more than two. > * The claim of multiple levels of angular momentum tells us that it is about > OAM and not SAM. The abstract of the debunking research (thanks Sverre for > posting) explicitly refers to OAM. Indeed photons can posses orbital angular momentum which can only interact with materials that have fairly special anisotropic properties (which is the reason I was not even bringing it up earlier). In order to talk to the oam component, one should subject RF photons to propagate in such medium as well. While possible in theory (and shown in optics using an "obscure" version of a halve wave plate), it would be a real challenge to observe this for RF where such materials are not available (someone correct me if I am wrong, I mostly work with optics).
However, an interesting topic and well worth looking into! I wonder if photon orbital angular momentum would be conserved in a non-linear process where the difference and sum generation occurs (usually just the sum is used, for example in second harmonic generation; similar to RF heterodyning) and the difference component would lie in RF (OK, perhaps in GHz range in practice...; near baseband anyway ;-)? So the idea would be to start with optical photons (prepared with oam information) at close wavelengths and then convert to RF (RF wavelength = difference between the two optical photons; angular momentum must be conserved). Unfortunately, this would not work for detection that well because high intensities are needed for the non-linear process. I would expect that the first place where this would show up (if possible at all) for RF would be nuclear magnetic resonance (NMR) experiments where I could see that the extra source of angular momentum could find applications there. I suspect that most people are getting bored already - so I will sign off... Best, Jussi Eloranta AA6KJ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
