Experimental demonstration of realizability of optical focus wave modes

The homogeneous scalar wave equation has a number of so-called localized wave (LW) solutions, instantaneous, Gaussian pulselike intensity distribution of which propagates without any spread or distortions in free space. Despite the undoubtedly intriguing properties and considerable effort that has been made to implement such wave fields, in the optical domain only their limiting case-the so-called Bessel-X pulses-has been experimentally launched so far. In this paper we report on experimental evidence of the optical realizability of the "fundamental" special case of the LW's-the focus wave modes.