Dark beams are wave fields carrying information in dark regions. We experimentally demonstrate dark beams that maintain a constant notch shape and size along a predetermined domain in free space. The energy is concentrated around the dark region with negligible sidelobes. These beams are generated with low-information-content phase-only diffractive elements in an on-axis configuration.
© 1996 Optical Society of America
Boris Spektor, Rafael Piestun, and Joseph Shamir, "Dark beams with a constant notch," Opt. Lett. 21, 456-458 (1996)