Focusing of scanning light beams below the diffraction limit without near-field spatial control using a saturable absorber and a negative-refraction material.
We show that a scanning light beam can be focused below the diffraction limit without the control of moving near-field elements using the combination of two main components: a light-controlled saturable absorber, which creates seed evanescent components from the beam, and a layer of negative-refraction material, which amplifies the evanescent waves. Focusing to spots with a FWHM in the range of 0.2-0.3 lambda is predicted. For slightly off-resonant input beams, an intensity-dependent phase shift leads to smaller spots.
Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2a, D-12489 Germany. gusakov@mbi-berlin.de
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A
Husakou
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J
Herrmann