Remote focusing of a light beam
The remote focusing of light in a graded-index medium via mode interference is demonstrated using exact analytical solutions of the wave equation. Strong focusing of a light beam occurs at extremely long distances and this repeats periodically with distance. The high efficiency transfer of a strongly focused subwavelength spot through an optical waveguide over large distances takes place with a period of revival. The simulated intensity distributions of a focused light beam and focusing efficiency (power in a central spot/total power) are presented. The far-field super-resolution imaging capabilities of a graded-index waveguide are also analyzed.