Observation of ultraslow optical solitons and vortex solitons in a room-temperature atomic gas via electromagnetically induced transparency

We report an experimental observation on the ultraslow optical solitons (USOSs) and vortex solitons (VSs) in a room-temperature, highly resonant atomic system via the electromagnetically-induced transparency. We show that when the input power of a probe laser exceeds a threshold, the probe beam can form USOSs and VSs, whose wave shapes are nearly invariant during propagation due to the exact balance between the transversal diffraction and self-focusing Kerr nonlinearity. We also show that optical solitons and VSs have an ultraslow propagation velocity of 10⁻⁵c (with c the speed of light in vacuum) and can be generated at a low light power of several microwatts. In addition, we provide theoretical analysis and carry out direct simulations, which agree well with the experimental results. Our findings pave the way for the generation of USOSs and VSs in room-temperature atomic systems and are useful for various applications in optical information processing and transmission.