Laser-induced radial birefringence and spin-to-orbital optical angular   momentum conversion in silver-doped glasses
  Samples of Ag$^+$/Na$^{+}$ ion-exchanged glass that have been subject to intense laser irradiation may develop novel optical properties, as a consequence of the formation of patterns of silver nanoparticles and other structures. Here, we report the observation of a laser-induced permanent transverse birefringence, with the optical axis forming a radial pattern, as revealed by the spin-to-orbital angular momentum conversion occurring in a probe light beam. The birefringence pattern can be modeled well as resulting from thermally-induced stresses arising in the silver-doped glass during laser exposure, although the actual mechanism leading to the permanent anisotropy is probably more complex. 
Jafar Mostafavi Amjad, Hamid Reza Khalesifard, Sergei Slussarenko,   Ebrahim Karimi, Lorenzo Marrucci, and Enrico Santamato
physics.optics