非傍轴衍射光束横截面上的光强及其能量传输

Light Intensity of Nonparaxial Diffracted Beams at Transverse Plane and Its Energy Transmission

运用角谱表示的矢量衍射理论,以平面波微小圆孔的非傍轴衍射为例,给出了垂直于光束传输方向的横截面上不同定义的三种光强(传统光强I、功率密度Jz、时间平均能流密度矢量的z分量〈Sz〉)的计算公式,并进行了详细的数值计算和比较研究.指出对微小孔衍射的能量传输,必须考虑光场的矢量特性.应用能流密度矢量S和功率流密度矢量J,分别计算了微小孔非傍轴衍射的透射系数,得到了一些新的结论.

Based on the vectorial diffraction theory of the angular spectrum representation and taken the nonparaxial diffraction of a small circular aperture as an example,the formulae for three different kinds of light intensity （the conventional intensity I.the power density Jz and the z component （Sz） of the timeaveraged Poynting vector） at transverse plane were obtained. Detailed numerical calculation was performed and the different results were compared. It is pointed out that vectorial property of the light field must be taken into account for the energy transmission of small aperture diffraction. The transmission coefficients of small circular aperture diffraction were calculated respectively by applying the energy flux density vector and the power flux density vector, and some new results were obtained.