部分相干径向偏振光束在自由空间中的传输

Propagation of partially coherent radially polarized beam in free space

基于2×2交叉谱密度矩阵的传输规律及部分相干光的相干与偏振的统一理论,研究了部分相干径向偏振光束在自由空间中的传输特性.理论分析和数值计算表明:部分相干径向偏振光束在传输过程中,其光强、斯托克斯参数及偏振度都会发生变化,光强由空心面包圈型逐渐变为实心,该现象与传输距离以及相干长度有关.同时在传输过程中,斯托克斯参数及偏振度的分布也与传输距离及相干长度有关,随着传输距离的增大,斯托克斯参数S1,S2的模值减小,偏振度随半径的分布曲线斜率逐渐降低,传输距离一定时,随着相干长度的增大,斯托克斯参数S1,S2的模值会随之增大,其有效分布区域向坐标轴收缩,偏振度随半径的分布曲线的斜率会随之增大.

Based on the propagation law of the 2×2 cross-spectral density matrix and the unified theory of coherence and polarization of partially coherent beams, the transmission characteristics of partially coherent radially polarized beams（PCRPB） have been investigated in the paper. It is shown that the intensity distribution, the degree of polarization（DOP） and the Stokes parameters will change after propagation through the free space. The doughnut beam spot of the partially coherent radially polarized beam becomes a solid beam, which is related to the propagation length and the coherence length. In addition, the degree of polarization and Stokes parameters in the propagation both relate to the propagation length and coherence length. With the increase of the propagation length, the modulus values of Stokes parameters S1 and S2 will decrease, the rate of the distribution of the DOP with radius will decrease. In a certain propagation length, with the increase of the coherence length, the modulus values of Stokes parameters S1 and S2 will increase, and their distribution will close to the axis, the rate of the distribution of the DOP with radius will increase.