Spatial focusing of surface polaritons based on cross-phase modulation

We theoretically study the spatial focusing of surface polaritons (SPs) in a negative index metamaterialatomic gas interface waveguide system, based on cross phase modulation (XPM) in a tripod type double electromagnetically induced transparency (EIT) scheme. In the linear region, we realize the low-loss stable propagation of SPs, and the group velocities of the probe and signal fields are well matched via double EIT. In the nonlinear region, we show that giant enhancement of the XPM can be obtained. Using a narrow optical soliton in free space, we realize spatial focusing of the SPs solitons, including bright, multi bright, and gray solitons. The full width at the half-maximum of the SPs soliton can be compressed to about ten nanometers, thus, even nanofocusing can be obtained. The results obtained her e have certain theoretical significance for nano-scale sensing, spectral enhancement and precision measurement.

Automated summary

In this study, we theoretically investigate the spatial focusing of surface polaritons (SPs) in a negative index metamaterial-atomic gas interface waveguide system using cross phase modulation (XPM) in a double electromagnetically induced transparency (EIT) scheme. We demonstrate low-loss stable propagation of SPs in the linear region and show giant enhancement of XPM in the nonlinear region, allowing for spatial focusing of SPs solitons. The results have certain theoretical significance for nano-scale sensing, spectral enhancement, and precision measurement.