method to generate non zero orbital angular momentum of light

Hi,

This paper shows the setup for generating a light beam with variable
OAM, using a variable phase delay box:

http://www.seas.harvard.edu/capasso/wp-content/uploads/publications/ncomms2293.pdf

I think the way it works is the two coherent beams are polarized 90
degrees to each other, and then one of them has a phase delay put on
it, which creates the non zero OAM resultant combined beam. I am not
100% sure that is how it works, but there is a diagram in the article
showing the setup. So it takes phase as well as polarization to make a
"vortex beam" so seems like not a good idea for increasing
communications bandwidth to me.

cheers,
Jamie

 

Have the current optical bandwidth limits been reached? I thought they
were not even close to using it up. I have utilized 10Gb/s optical
switching modules.

 

from that description it sounds a lot like circular polarisation

 

Circular polarization is due to light's spin angular momentum; OAM
is not:

http://en.wikipedia.org/wiki/Angular_momentum_of_light

http://en.wikipedia.org/wiki/Light_spin_angular_momentum

http://en.wikipedia.org/wiki/Light_orbital_angular_momentum

Check out the diagram on page 3 of your cited document. The fork
hologram is characteristic of OAM.


Mark L. Fergerson

 

Hi,

Thanks for the links, really useful pages.

cheers,
Jamie