We have observed very long trapping of ultraslow light pulse far beyond the conventional limitation of spin coherence relaxation time in an optical medium using double electromagnetically induced transparency-based spin coherence gratings.
Light control by another light has drawn much attention in nonlinear quantum optics. Achieving all-optical control of the refractive index has been a key issue in all-optical information processing. Ultraslow light has been a good candidate for this purpose, where a giant phase shift can be achieved. The recent presentation of stationary light utilizing ultraslow light is an advanced example of such research. The stationary light functions as cavity quantum electrodynamics, where no high-Q-factor mirror pair is needed. In this paper, we report on two-color halted light pulses inside a solid medium, where the trapping time is comparable with that of ultraslow light but is much longer than quantum mapping storage time. The observed two-color halted light is achieved by means of double Raman optical field-excited spin coherence gratings, where slow light enhanced backward nondegenerate four-wave mixing processes play a major role.
Abstract We propose a scheme to realize the manipulation of a weak signal pulse by ultraslow optical soliton in a coherent inverted-Y-type atomic system via double electromagnetically induced transparency (EIT). Based on Maxwell-Bloch equations, we derive nonlinear equations governing the spatial-temporal evolution of the probe and signal pulse envelopes. We show the giant enhancement of optical Kerr nonlinearity can be obtained under the condition of the double EIT, which results in the generation of a (2+1)-dimension optical soliton and can realize the manipulation of a weak signal pulse. Applying a far-detuned laser field to the system, we find that a weak signal pulse can be trapped by a (3+1)-dimension light bullet. In particular, the trajectories of the light bullet and trapped signal pulse can be manipulated and controlled by introducing a Stern–Gerlach gradient magnetic field. The results predicted here may not only open a route for the study of weak-light nonlinear optics but also have potential applications in the precision measurements and optical information processing and transmission.
We present observations of self induced ultraslow light in a persistent spectral hole-burning rare-earth doped crystal. The observed group delay (velocity) is as long as 40 micros (75 m/s), which is comparable to that obtained using electromagnetically induced transparency or coherent population oscillations. We analyze the observed ultraslow light as a function of frequency detuning, light intensity, and atom population (oscillator strength). The present observation of ultraslow light in a persistent spectral hole-burning medium gives potentials to all-optical information processing such as on-demand all-optical buffer memories.