A relativistically intense, ultrashort laser pulse with purely spin angular momentum produces second-harmonic radiation with equal parts of both spin and orbital angular momentum when focused into a plasma. The orbital contribution is due to an azimuthal phase variation that arises in the nonlinear current density. This phase variation is associated with the radial nonuniformity driven by ponderomotive blowout.
© 2009 Optical Society of America
Original Manuscript: August 12, 2009
Manuscript Accepted: September 15, 2009
Published: October 22, 2009
D. F. Gordon, B. Hafizi, and A. Ting, "Nonlinear conversion of photon spin to photon orbital angular momentum," Opt. Lett. 34, 3280-3282 (2009)