Spin-constrained orbital-angular-momentum control in high-harmonic generation

The interplay between spin and orbital angular momentum in the up-conversion process allows us to control the macroscopic wave front of high harmonics by manipulating the microscopic polarizations of the driving field. We demonstrate the control of orbital angular momentum in high-harmonic generation from both solid- and gas-phase targets using the selection rules of spin angular momentum. The gas-phase harmonics extend the control of angular momentum to the extreme-ultraviolet wavelength. We also propose a bicolor scheme to produce spectrally separated extreme-ultraviolet radiation carrying orbital angular momentum.