Ultraslow optical solitons in atomic media with spontaneously generated coherence

We propose a new scheme to generate stable ultraslow optical solitons in lifetime-broadened three-state V-type media via spontaneously generated coherence (SGC). We show that in the linear propagation regime, SGC in the system can result in a significant change of dispersion and absorption, which may be used to completely eliminate absorption and greatly reduce the group velocity of the probe field. In the nonlinear propagation regime, SGC can largely enhance the Kerr nonlinearity of the system. By means of SGC, stable optical solitons with ultraslow propagating velocity and ultralow generation power can be produced. Different from previous works, ultraslow optical solitons obtained in the present system based on SGC have much smaller attenuation during propagation and can be created by using only one laser field.