کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
848787 | 909251 | 2011 | 5 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Torque equations for spin and orbital angular momenta of radiation fields and Faraday effect Torque equations for spin and orbital angular momenta of radiation fields and Faraday effect](/preview/png/848787.png)
The spin angular momentum S of light has never been linked to the Faraday rotation of light traveling in an optically active medium possessing a rotational invariance of a crystal, because there was no helicity term associated with the phase shift in the previous torque equation for S. In order to relate the change in S with time to the Faraday rotation, therefore, we derived an exact torque equation for S. As a result, a magnetic helicity term appeared in a new torque equation for S, so that one-half of the phase shift derived from the helicity term was equivalent to the Faraday rotation angle. However, the orbital angular momentum L had no relation to the Faraday rotation. It was thus clarified that the change in S with time is related to the Faraday rotation angle of light traveling in an optically active medium, owing to the appearance of the helicity term without a rotational invariance around the optical axis. It was also demonstrated theoretically that the Faraday rotation is accompanied by a torque acting on the crystal so that the total angular momentum of light and matter is conserved.
Journal: Optik - International Journal for Light and Electron Optics - Volume 122, Issue 23, December 2011, Pages 2119–2123