Controlling the transition of bright and dark states via scanning dressing field

In a numerical investigation, we demonstrate the existence and curious evolution of vortices in a ladder-type three-level nonlinear atomic vapor with linear, cubic, and quintic susceptibilities considered simultaneously with the dressing effect. We find that the number of beads and topological charge of the incident beam, as well as its size, greatly affect the formation and evolution of vortices. To determine the number of induced vortices and the corresponding rotation direction, we give common rules associated with the initial conditions coming from various incident beams.

Optical vortices induced in nonlinear multilevel atomic vapors

Optical vortices induced in nonlinear multilevel atomic vapors.

Cavity linewidth narrowing via double-dark resonances is experimentally observed using the Rb87 Zeeman splitting sublevels. With the steep dispersion led by the interacting dark resonances in the tripod-type electromagnetically induced transparency system, we narrow the cavity linewidth to 250 kHz at room temperature. Furthermore, the position of this ultranarrow cavity linewidth can be tuned in a 60 MHz coupling field detuning range.

Realization of cavity linewidth narrowing via interacting dark resonances in a tripod-type electromagnetically induced transparency system

Transmissivity of up to 200% has been observed in an absorption imaging study of electromagnetically induced transparency in cold sodium atoms, when a focused coupling beam is applied near the edge of the atom cloud. The signal behavior strongly depends on the frequency difference between the probe beam and the coupling beam. Such high transmissivity can be attributed to the strong focusing effect of the probe beam, when it propagates in a medium with spatially inhomogeneous refractive index induced by the coupling beam. A detailed numerical analysis based upon the Maxwell propagation equations is presented.

27aWM-1 Absorption imaging of electromagnetically-induced transparency in cold sodium atoms

We experimentally report that angle-control dynamics in the nonlinear propagation of the images of the probe, generated four-wave mixing (FWM) and fluorescence signals beams in FWM process in a cascade three-level, as well as a two-level atomic systems. It is shown that, by changing the angles between pumping fields and dressing fields, respectively, the characteristics of the measured signals including the spectra intensity and spatial images can be controlled to display many effects, including the electromagnetically induced transparency and absorption (EIT and EIA, respectively) and Autler-Townes splitting. In particular, we demonstrate the angle-controlled switching from EIA to EIT in probe transmission or from enhancement to suppression in FWM signal. Additionally, we also illustrate the interaction between spatial characteristics and spectra intensities of weak fields. The studies can be very useful in producing all optical-signal-processing devices, such as spatial beam splitters, routers, and switches.

Observation of Angle Switching of Dressed Four-Wave Mixing Image

We show that polarization properties of the suppression and enhancement as well as the Autler-Townes (AT) splitting of two coexisting six-wave mixing (SWM) processes in multi-Zeeman levels atomic system. By scanning the frequency detuning of the dressing field, we observe the suppression and enhancement as well as the AT splitting of the two coexisting SWM processes with the different polarized probe beams. Different polarization states of the probe beam can select different transitions among multi-Zeeman levels and different dressing strengths. The AT splitting separations get slightly large as the probe beam changes from the linearly polarized state to the circularly polarized one. Under the conditions of different dressing fields, the polarization dependence of the SWM enhancement and suppression shows the inverse variation. Theoretical calculations are carried out, which are in good agreement with the experimental results.

Polarized Suppression and Enhancement of Six-Wave Mixing in Electromagnetically Induced Transparency Window

We experimentally observe the interplay among coexisting multiwave-mixing (MWM) signals via multiple electromagnetically induced transparency (EIT) windows, including two ladder-type EIT windows and one V-type EIT-like window in a five-level atomic system of Rb85. In the presence of these EIT windows, one can control the interplay between these MWM signals easily by changing the frequency detuning. Meanwhile, we also report the spatial and temporal interferences with a femtosecond time scale among three coexisting MWM signals in two overlapped EIT windows.

Interference of three multiwave mixings via electromagnetically induced transparency

We report our observations on enhancement and suppression of spatial four-wave mixing (FWM) images and the interplay of four coexisting FWM processes in a two-level atomic system associating with three-level atomic system as comparison. The phenomenon of spatial splitting of the FWM signal has been observed in both x and y directions. Such FWM spatial splitting is induced by the enhanced cross-Kerr nonlinearity due to atomic coherence. The intensity of the spatial FWM signal can be controlled by an additional dressing field. Studies on such controllable beam splitting can be very useful in understanding spatial soliton formation and interactions, and in applications of spatial signal processing.

Controlling cascade dressing interaction of four-wave mixing image

We investigate the polarization dependence of eight coexisting four-wave mixing (FWM) signals in a two-level atomic system. The intensities and polarization states of coexisting FWM signals are modulated by the polarization configurations and frequency detunings of the incident fields. The suppression and enhancement due to the dressing effects present different polarization dependences. Both the mutual-dressing effect and the self-dressing effect are considered to explain the observed phenomena.

Suling Sang

Papers

Observation of Angle Switching of Dressed Four-Wave Mixing Image

Polarized Suppression and Enhancement of Six-Wave Mixing in Electromagnetically Induced Transparency Window

Interference of three multiwave mixings via electromagnetically induced transparency

Controlling cascade dressing interaction of four-wave mixing image

Coexisting polarized four-wave mixing processes in a two-level atomic system