Controlled spatial beam splitter using four-wave-mixing images

Abstract

We report our experimental observations of spatial shift and splitting of four-wave mixing ͑FWM͒ signal beams induced by additional dressing laser beams. These effects are caused by the enhanced cross-Kerr nonlinearity due to atomic coherence in a two-level atomic system. The spatial separation and number of the split FWM beams can both be controlled by the intensity of the dressing beam, the Kerr nonlinearity, and atomic density. Theoretical results agree quite well with the observations. Studies of such controlled beam splitting can be very useful in understanding spatial soliton formation and interactions, and in applications for spatial signal processing.

Spatial interplay of two four-wave mixing images

“…In addition, an electromagnetically induced grating (EIG) resulting from a strong standing wave interacting with the atomic medium, which can diffract a weak incident field into a high-order direction, is profoundly developed in multilevel atoms [17,18]. Recently, we have observed spatial shift, spatial splitting, gap solitons, and dipole solitons of the FWM beams generated in multilevel atomic systems [19][20][21][22], which can be well controlled by additional dressing laser beams via the cross-phase modulation (XPM).…”

Modulated vortex solitons of four-wave mixing

“…1(a)] in the direction shown at the lower right corner of Fig. 1 E are the dominant ones in the experiment due to phase-matching and chosen beam intensities [17,18]. According to these FWM phase matching conditions, we can obtain the coherence lengths in the two-level system as E , respectively.…”

“…In this letter, we experimentally demonstrate the formations of modulated vortex solitons in two generated four-wave mixing (FWM) waves in a two-level, as well as a cascade three-level, atomic systems. These vortex solitons are created by the interference patterns by superposing three or more waves, and by the greatly enhanced cross-Kerr nonlinear dispersion due to atomic coherence [16,17]. k and F2 k with five beams 1…”

“…by calculating the density-matrix element (3) 10 ρ [16,17]. In addition, the Doppler effect and power broadening effect are considered in calculating these Kerr nonlinear coefficients.…”

Propagation of optical vortices in a nonlinear atomic medium with a photonic band gap

“…Accompanied with the development of the transferring method, the evolutions of OV experiencing linear or nonlinear optical processes are experimentally studied in electromagnetically induced transparency (EIT) [7,8], second-harmonic generation [9], four-wave mixing (FWM) [10], and parametric downconversion processes [11]. During the interactions between lights and media, the properties of the OV can be unavoidably modulated by the nonlinear effects such as Kerr-type nonlinearity [12][13][14], which can impose effects on the applications taking advantages of the spatial intensity distribution of OV such as entangled states [15] and logical gates for quantum computation [16,17].…”