A pulse transmitted through a helical vortex phase mask undergoes a temporal Hilbert transform. The fluence transmitted into the unfavorable plane wave mode is found to increase as the square of the bandwidth and, to first order, is independent of the topological charge.
© 2005 Optical Society of America
Grover A. Swartzlander, Jr., "Broadband nulling of a vortex phase mask," Opt. Lett. 30, 2876-2878 (2005)