We study the spatial behavior of a deflected beam in a coherent A-type three-level atomic medium with an inhomogeneous control laser.When the Rabi coupling by the control laser is in a Gaussian profile,the spatialdependent refraction index of the atomic medium will result in a beam splitting as well as the deflection of the slow probe light under electromagnetically induced transparency.In terms of the phase difference between the two splitting beams and the position of the splitting,the possible interpretation of the splitting is given in theory.
We investigate the nonlinear modes in a rotating double well potential with PT symmetry. Focus on the existence and stability of the nonlinear PT modes in this system, we found that five types of PT modes can stably exist by given certain parameter settings. The multistable area between these modes are studied numerically and the bistable and tristable areas are delimited. With different input trial wavefunctions, five types of solitary wave modes are identified. We found that the rotating of the potential can significantly affect the power flow of the fundamental harmonic mode, whose effect is absent for the other modes.
Lensless ghost diffraction with partially coherent sources is investigated theoretically and numerically.Based on the classical optical coherent theory and the Gauss–Shell model of the partially coherent sources,we derive an analytical imaging formula of lensless ghost diffraction(LGD).Using this formula,we can see the effects of the transverse size and coherence of the sources,the detector size and defocusing length on the quality of LGD.Numerical results are presented to show that for different detector sizes and defocusing lengths,high quality LGD can be realized by using sources with appropriate transverse sizes and coherent widths.These findings can be used to choose the optimal parameters in the design of a realistic LGD system.
Splitting white light into its constituent spectral components has been of interest ever since Newton first discovered the phenomenon of color separation.Many devices have since been conceived to achieve efficient wavelength separation,yet a large number of applications,e.g.,in display technology,still use simple color absorption or rejection filters that absorb or reflect unwanted wavelengths,thus wasting luminous energy.Here,we demonstrate a novel microsized device concept that enables efficient color routing.The device operation is based on differential material dispersion in a waveguide array,which causes different wavelength signals to couple selectively into appropriate waveguides.A theoretical power delivery of greater than 50%for a tricolor wavelength router is obtained,compared to 33%expected from geometry alone.The principle of operation is demonstrated experimentally for a dual-color light field,where we achieve a higher than 70%routing efficiency(compared to 50%from geometry),thus highlighting the feasibility of this novel and promising approach.
Yi-Kun LiuSi-Cong WangYong-Yao LiLi-Yan SongXiang-Sheng XieMing-Neng FengZhi-Ming XiaoShao-Zhi DengJian-Ying ZhouJun-Tao LiKam Sing WongThomas F Krauss
