Suling Sang

Observation of Angle Switching of Dressed Four-Wave Mixing Image

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.

Controlling cascade dressing interaction of four-wave mixing image

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.

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

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.

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

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.

Spatial interplay of two four-wave mixing images

We investigate the interplay between the two components of the four-wave mixing (FWM) beams in a ladder-type three-level atomic system. The interplay, including the shift and splitting of the two FWM beams and their intensity modulation, depends on the frequency detuning and the angles as well as the powers of the pump fields. The x-directional splitting due to the cross-phase modulation and y-directional splitting because of electromagnetically induced gratings of FWM beams are investigated. Both the theoretical and experimental results exhibit that the spatial separation and the number of the FWM signals can be well controlled by additional dressing laser beams. Such studies not only can be very useful in better understanding the formation of spatial solitons but also have potential applications in signal processing.

Multidressing interaction of four-wave mixing image in three-level atomic system

We demonstrate different dressed processes of four-wave mixing (FWM), as changing the powers of the probe, pump, and dressing fields, respectively, in ladder-type three-level system. It is demonstrated that scanning detuning of the dressing field can lead to the direct detection of the dressing effects and the interaction between the dressing fields, compared with scanning that of the probe field. Moreover, by respectively controlling the powers of the dressing, pump, and probe fields, the enhancement and suppression of FWM signals can be switched sensitively. Meanwhile, the spatial splitting in y direction of FWM signal due to the cross-phase modulation and electromagnetically induced gratings is observed, respectively. Such nonlinear signal with switchable enhancement has potential applications in optical switching, optical communication, and quantum information processing.