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Register a new userSteep optical wave group velocity reduction and storage of light without electromagnetically induced transparency
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Authors
M. Kozuma
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We report experimental investigationd of optical pulse group velocity reduction and probe pulse regeneration using a Raman scheme. The new scheme which does not rely on the on-one-photon resonance electromagnetically induced transparency (EIT), has many advantages over the conventional method which critically relys on the transparency window created by an EIT process. We demonstrate significant reduction of group velocity, less probe field loss, reduced probe pulse distortion, and high probe pulse regeneration efficiency.
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The broadband parametric fluorescence pulse (probe light) with center frequency resonant on 87Rb D1 line was injected into a cold atomic ensemble with coherent light (control light). Due to the low gain in the parametric down conversion process, the probe light was in a highly bunched photon-pair state. By switching off the control light, the probe light within the electromagnetically induced transparency window was mapped on the atoms. When the control light was switched on, the probe light was retrieved and frequency filtered storage was confirmed from the superbunching effect and an increase of the coherence time of the retrieved light.
We experimentally demonstrate coherent amplification of probe field in a tripod-type atoms driven by strong coupling, signal and weak probe fields. We suppress linear and nonlinear atomic absorptions for resonant and near resonant probe via double electromagnetically induced transparency (DEIT). Combining these advantages of suppressed absorption along with temperature- or atomic-density-controlled transfer of population(ToP) between hyperfine ground states, we can induce near-resonant amplification of probe through stimulated Raman scattering(SRS) pumped by low-intensity signal field. The increased population difference of initial and final states of SRS due to increased ToP rate, together with reduced absorption at the second EIT window in an optically thick Cesium vapor, gives rise to highly effective coherent amplification.
We report on the delay of optical pulses using electromagnetically induced transparency in an ensemble of cold atoms with an optical depth exceeding 500. To identify the regimes in which four-wave mixing impacts on EIT behaviour, we conduct the experiment in both rubidium 85 and rubidium 87. Comparison with theory shows excellent agreement in both isotopes. In rubidium 87, negligible four-wave mixing was observed and we obtained one pulse-width of delay with 50% efficiency. In rubidium 85, four-wave-mixing contributes to the output. In this regime we achieve a delay-bandwidth product of 3.7 at 50% efficiency, allowing temporally multimode delay, which we demonstrate by compressing two pulses into the memory medium.
We propose a scheme to generate temporal vector optical solitons in a lifetime broadened five-state atomic medium via electromagnetically induced transparency. We show that this scheme, which is fundamentally different from the passive one by using optical fibers, is capable of achieving distortion-free vector optical solitons with ultraslow propagating velocity under very weak drive conditions. We demonstrate both analytically and numerically that it is easy to realize Manakov temporal vector solitons by actively manipulating the dispersion and self- and cross-phase modulation effects of the system.
We show that an alkali atom with a tripod electronic structure can yield rich electromagnetically induced transparency phenomena even at room temperature. In particular we introduce double-double electromagnetically induced transparency wherein signal and probe fields each have two transparency windows. Their group velocities can be matched in either the first or second pair of transparency windows. Moreover signal and probe fields can each experience coherent gain in the second transparency windows. We explain using a semi-classical-dressed-picture to connect the tripod electronic structure to a double-Lambda scheme.
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