Zheng Huai-Bin

Enhancement and suppression of two coexisting six-wave-mixing processes

The enhancement and suppression of the two coexisting six-wave mixing (SWM) processes via atomic coherence have been observed. In the presence of mutual dressing between two SWM signals, the self-dressing effect causes the Autler-Townes (AT) splitting of the SWM signals and the external-dressing effect makes the SWM signals enhanced or suppressed. In addition, the power dependencies of the enhancement and suppression of SWM processes are studied. Theoretical calculations are carried out, which are in good agreement with the experimental results.

Spatial Four Wave Mixing, Probe Images, and Fluorescence Signals in Dressed Three-Level System

We investigate the spatial images of the probe, generated four wave mixing (FWM) signal and the accompanying fluorescence spectrum signal simultaneously in FWM process in a cascade three-level atom...

Enhancement and suppression of spatial splitting four-wave mixing in atomic medium

We experimentally report on the evolution from singly-dressed to doubly-dressed four-wave mixing (FWM) process by controlling the powers of the probe, the pump and the dressing fields respectively. The differences in the enhancement and the suppression of FWM signal between the two-level and cascade three-level atomic systems are observed and explained by the multi-dressed effect theoretically. Both the x direction and the y direction spatial splittings of the degenerate-FWM (DWFM) beams are obtained. We also investigate the switch between the enhancement and the suppression of the DWFM signals and between its spatial splittings in x direction and y direction. The spatial splittings in x direction and y direction can be controlled by the relative position and the intensity of the involved laser beams. Such a study can be useful for optimizing the efficiency of the FWM process and providing potential applications in spatial signal processing.

Seven Odd-Order Multi-Wave Mixing Spectra in a Five-Level Atomic System

In a K-type five-level atomic system, seven odd-order multi-wave mixing (MWM) processes are considered. We can distinguish the MWM signals by selectively blocking different laser beams and changing frequency detuning. We study the interaction in seven odd-order MWM processes in a five-level atomic system and demonstrate the existence of mutual suppression of seven odd-order MWM processes by setting dual electromagnetically induced transparency windows as separated or merged.

Spatial Dispersion Induced by Cross-Phase Modulation

We demonstrate our experiment of controlling spatial displacements of the probe beam induced by the cross-Kerr effect in a three-level V-type atomic system. By increasing the atomic density or the intensity of strong control laser beams, spatial displacements are enhanced. We further study the difference of effects from the atomic density and the laser intensity. In addition, the spatial displacement efficiencies of the probe beam in different energy level atomic systems are compared. Such studies of controlling spatial displacements can have potential applications in soliton deflection, spatial optical switch and generating spatially correlated (entangled) laser beams in multi-level EIT systems.

Co-existence of multi-wave mixing in an opening five-level atomic system

We study the co-existence of multi-wave mixing processes in an open five-level atomic system affected by strong coupling fields. Competition among four-wave mixing （FWM） with two dressing fields, the six-wave mixing （SWM） with one dressing field as well as the eight-wave mixing （EWM） propagating along the same direction can be evoked by adjusting laser beams because these multi-wave mixing signals are induced by atomic coherence between common levels. With the dressing fields properly controlled, the FWM and SWM signals can be suppressed while the EWM signals enhanced in the beam. We also amply analyze the difference between the parallel-cascade and sequentical-cascade doubly dressing mechanisms in doubly-dressed four-wave mixing （DDFWM） processes.

Coexisting Raman- and Rayleigh-Enhanced Four-Wave Mixing in Femtosecond Polarization Beats

Based on the polarization interference of Raman- and Rayleigh-enhanced four-wave mixing processes, heterodyne detection of the Raman, Rayleigh and coexisting Raman and Rayleigh femtosecond difference-frequency polarization beats is investigated in the cw and the three Markovian stochastic models, respectively. These two processes exhibit asymmetric and symmetric spectra, respectively, and the thermal effect in them can be suppressed by a field-correlation method. Such studies of coexisting Raman- and Rayleigh-enhanced four-wave mixing processes can have important applications in coherence quantum control, and quantum information processing.

Four-wave mixing and six-wave mixing in a four-level confined atomic system

We have investigated coexisting four-wave mixing and six-wave mixing (SWM) in ultra-thin, micrometre and long vapour cells. There exists competition between Dicke-narrowing features and polarization interference in the micrometre cell. The oscillation behaviour of SWM signal intensities and linewidths results from destructive interference. With a larger destructive interference, the SWM signal in ultra-thin cells shows a narrow spectrum, in contrast to the long cell case. Due to the Dicke-narrowing features, a narrow spectrum can be obtained, and such spectra can be used for high precision measurements and metrological standards.

Observation of the near transform-limited high-resolution tunable far-ultraviolet light

This paper studies the near transform-limited high-resolution tunable far-ultraviolet light which is generated by narrow-band tunable light both theoretically and experimentally. It shows the theoretical work about conversion efficiency of sum-frequency, which is restricted by phase-matching angle, walk-off angle and phase distortion and so on, and sets experiment to check this work successfully. Also the origin of chirp of dye laser is analysed.

Phase dispersion of Raman and Rayleigh-enhanced four-wave mixings in femtosecond polarization beats

Based on color-locking noisy field correlation in three Markovian stochastic models, phase dispersions of the Raman- and Rayleigh-enhanced four-wave mixing (FWM) have been investigated. The phase dispersions are modified by both linewidth and time delay for negative time delay, but only by linewidth for positive time delay. Moreover, the results under narrowband condition are close to the nonmodified nonlinear dispersion and absorption of the material. Homodyne and heterodyne detections of the Raman, the Rayleigh and the mixing femtosecond difference-frequency polarization beats have also been investigated, separately.