A Possibility for using an APPLE undulator to generate a photon beam with transverse optical modes

Sasaki, Shigemi*; McNulty, I.*; Shimada, Taihei

Proceedings of 2007 Particle Accelerator Conference (PAC '07) (Internet), p.1142 - 1144, 2007/06

https://doi.org/10.1109/PAC.2007.4441009

Photons that carry orbital angular momentum are of great interest to the optics communities. This property of photon beams was recently demonstrated in the X-ray regime and may be useful to probe angular momentum in matter. However, by comparison to the visible light, it is difficult to fabricate efficient achromatic optics to generate these optical modes in X-rays. In spite of these inconveniences, there has been no investigation of the possibility of using a synchrotron light source to directly generate an X-ray beam with transverse optical modes. In this paper, we investigate use of an APPLE-type undulator for generating L-G and H-G mode beams. We find that the 2nd harmonic radiation in the circular mode corresponds to an LG beam with =1, and the 2nd harmonic in the linear mode corresponds to an HG beam with =1. The combination of an APPLE device and monochromator optics may provide an opportunity for a new type of experimental research in the synchrotron radiation community.