Angular dependence of spatial frequency modulation in diffusion media

Abstract

An optical field will undergo coherent diffusion when it is mapped into thermal-motioned atoms, e.g., in a slow or storage light process. As was demonstrated before, such diffusion effect is equivalent to a spatial low-pass filter attenuating the high spatial frequency (SF) components of the optical field. Here, employing electromagnetically induced transparency (EIT) based light storage in hot atomic vapor, we demonstrate that the angular deviation between the control and probe beams could be utilized as a degree of freedom to modulate the SF of the probe beam. The principle is to change the diffusion-induced low-pass filter into a band-pass filter, whose SF response can be tuned by varying the direction and magnitude of the angular deviation. Transverse multimode light fields, such as optical images and Laguerre-Gaussian modes are utilized to study such SF modulation. Our findings could be broadly applied to the fields of quantum information processing, all-optical image manipulation and imaging through diffusive media.

Shape-preserving storage of elegant Ince-Gaussian modes in warm atomic vapor

“…In order to attain the retrieved beams with high fidelity, researchers have proposed various schemes, such as the atomic analogue of the optical phase-shift lithography [19,20] , storing the Fourier transform of the image [12] , using the correlation imaging technique [21] , and adjusting the angular deviation between the probe beam and the control beam [22] . Nevertheless, additional operation of the light field is required in all of these approaches, which increases the operation difficulty and system complexity.…”