Elimination, reversal and directional bias of optical diffraction

Abstract

Electromagnetically induced transparency in an atomic gas can slow the propagation of images. It is now shown that the diffraction of such images as they propagate can be controlled and even eliminated. This is achieved by using atomic diffusion to influence the spreading of the image. Any image, imprinted on a wave field and propagating in free space, undergoes a paraxial diffraction spreading. The reduction or manipulation of diffraction is desirable for many applications, such as imaging, wave-guiding, microlithography and optical data processing. As was recently demonstrated, arbitrary images imprinted on light pulses are dramatically slowed1,2 when traversing an atomic medium of electromagnetically induced transparency3,4 and undergo diffusion due to the thermal atomic motion5,6. Here we experimentally demonstrate a new technique to eliminate the paraxial diffraction and the diffusion of slow light, regardless of its position and shape7. Unlike former suggestions for diffraction manipulation8,9,10,11,12, our scheme is linear and operates in the wavevector space, eliminating the diffraction for arbitrary images throughout their propagation. By tuning the interaction, we further demonstrate acceleration of diffraction, biased diffraction and induced deflection, and reverse diffraction, implementing a negative-diffraction lens13. Alongside recent advances in slow-light amplification14 and image entanglement15, diffraction control opens various possibilities for classical and quantum image manipulation.

Cite this article

Firstenberg, O., London, P., Shuker, M. et al. Elimination, reversal and directional bias of optical diffraction. Nature Phys 5, 665–668 (2009). https://doi.org/10.1038/nphys1358

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