High-Resolution All-Optical Imaging of Multimode Profiles in a Saturated Absorption Medium

We proposed an all-optical imaging technique based on saturated absorption spectroscopy in an atomic vapor. The atoms are driven by a counter-propagating strong pump laser on a transition which is probed by a comparatively weak probe laser. We show that the different orders of Hermite-Gaussian beam carried by pump laser can be efficiently imaged onto a Gaussian-shaped probe laser within a Rayleigh length. The feature size of transmitted probe beam is reduced by a factor 4 when compared to the original pump beam. To generalize the scheme, an arbitrary image imprinted initially on pump beam is successfully transferred onto the output probe beam. Such a method of high resolution multimode imaging may find potential applications in all-optical imaging and lithography technologies.