Photon self-induced spin-to-orbital conversion in a terbium-gallium-garnet crystal at high laser power
Year: 2010
Authors: Mosca S., Canuel B., Karimi E., Piccirillo B., Marrucci L., De Rosa R., Genin E., Milano L., Santamato E.
Autors Affiliation: Univ Naples Federico II, Dipartimento Sci Fis, I-80126 Naples, Italy; Ist Nazl Fis Nucl, Sez Napoli, I-80126 Naples, Italy; EGO, Cascina, PI, Italy; CNISM Consorzio Nazl Interuniv Sci Fis Materia, Naples, Italy; CNR INFM Coherentia, I-80126 Naples, Italy.
Abstract: In this paper, we present experimental evidence of a third-order nonlinear optical process, self-induced spin-to-orbital conversion (SISTOC) of the photon angular momentum. This effect is the physical mechanism at the origin of the depolarization of very intense laser beams propagating in isotropic materials. The SISTOC process, like self-focusing, is triggered by laser heating leading to a radial temperature gradient in the medium. In this work we tested the occurrence of SISTOC in a terbium-gallium-garnet rod for an impinging laser power of about 100 W. To study the SISTOC process we used different techniques: polarization analysis, interferometry, and tomography of the photon orbital angular momentum. Our results confirm, in particular, that the apparent depolarization of the beam is due to the occurrence of maximal entanglement between the spin and orbital angular momentum of the photons undergoing the SISTOC process. This explanation of the true nature of the depolarization mechanism could be of some help in finding novel methods to reduce or to compensate for this usually unwanted depolarization effect in all cases where very high laser power and good beam quality are required.
Journal/Review: PHYSICAL REVIEW A
Volume: 82 (4) Pages from: 43806-1 to: 43806-6
KeyWords: Nd-yag LaserDOI: 10.1103/PhysRevA.82.043806Citations: 13data from “WEB OF SCIENCE” (of Thomson Reuters) are update at: 2024-10-20References taken from IsiWeb of Knowledge: (subscribers only)