Steep optical-wave group-velocity reduction and “storage” of light without on-resonance electromagnetically induced transparency

We report on experimental investigation of optical-pulse group-velocity reduction and probe-pulse ``regeneration'' using a Raman scheme. This scheme, which does not rely on the commonly used on-one-photon-resonance electromagnetically induced transparency (EIT) process, has many advantages over the conventional method that critically relies on the transparency window created by an EIT process. We demonstrate significant reduction of the group velocity, less probe-field loss, reduced probe-pulse distortion, and high probe-pulse regeneration efficiency.