Spatial focusing of a time-reversed pulse

Focusing of a pulse with the focal-spot size λ/14, obtained experimentally by the method of time reversal of a wave is reported in [1], where it is treated as overcoming of the diffraction limit. This and other statements in [1] implying new physical concepts of time-reversed waves need detailed analysis. We consider the physical nature of the spatial focusing of a time-reversed pulse and show that the focal-spot narrowing below the diffraction limit results from observation of the field of a source located in the near zone of the observation point. This phenomenon cannot be treated as overcoming of the diffraction limit and is not related to the new physical concepts of waves. © 2003 Plenum Publishing Corporation.