Abstract
There is recent interest in the use of light beams carrying orbital angular momentum (OAM) for creating multiple channels within free-space optical communication systems. One crucial issue is that, for a given beam size at the transmitter, the beam divergence angle increases with increasing OAM. Therefore the larger the value of OAM, the larger the aperture required at the receiving optical system if the efficiency of detection is to be maintained. Confusion exists as to whether this divergence scales linearly with, or with the square root of, the beam’s OAM. We clarify how both these scaling laws are valid, depending upon whether it is the radius of the waist of the beam’s Gaussian term or the radius of rms intensity of the beam that is kept constant while varying the OAM.
Highlights
February 2015Abstract (s) and the title of the There is recent interest in the use of light beams carrying orbital angular momentum (OAM) for creatwork, journal citation and DOI
Over the past 20 years there has been a growing interest in the orbital angular momentum (OAM) of light, which is carried by any optical beam possessing helical phase fronts [1]
Rather than the beam waist w0, or the radius of maximum intensity r (Imax), the divergence of a light beam is governed by the standard deviation of its spatial distribution, rrms [8, 9]
Summary
Abstract (s) and the title of the There is recent interest in the use of light beams carrying orbital angular momentum (OAM) for creatwork, journal citation and DOI. The larger the value of OAM, the larger the aperture required at the receiving optical system if the efficiency of detection is to be maintained. Confusion exists as to whether this divergence scales linearly with, or with the square root of, the beam’s OAM. We clarify how both these scaling laws are valid, depending upon whether it is the radius of the waist of the beam’s Gaussian term or the radius of rms intensity of the beam that is kept constant while varying the OAM
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have