Senthilkumaran Paramasivam, Bahl Monika
Opt Express. 2015 May 4;23(9):10968-73. doi: 10.1364/OE.23.010968.
We report an interesting observation in the formation of Young's fringes from a two pinhole arrangement illuminated by waves from the neighborhood of a zero of an optical phase singularity. Spacing of the Young's fringes appears to defy the dependence of pin-hole separation. But for larger pinhole separation such an anomalous phenomenon is not discernible. The experiments show that the fringe spacing is governed by the stronger local phase gradient near the vortex core that also has a radial part. Many diffraction experiments reported so far have missed this aspect as the phase gradient in a vortex beam is normally considered to have only azimuthal and longitudinal components. This work reveals the vortex core structure and is the first experimental evidence to the existence of a radial component of this phase gradient.
我们报告了一个有趣的观察结果，该观察结果涉及由光学相位奇点零点附近的波照亮的双针孔装置形成杨氏条纹的过程。杨氏条纹的间距似乎与针孔间距的依赖性相悖。但对于较大的针孔间距，这种异常现象并不明显。实验表明，条纹间距由涡旋核附近更强的局部相位梯度决定，该相位梯度也有一个径向分量。到目前为止报道的许多衍射实验都忽略了这一方面，因为涡旋光束中的相位梯度通常被认为只有方位角和纵向分量。这项工作揭示了涡旋核结构，并且是该相位梯度径向分量存在的首个实验证据。
