CNR-SPIN and Dipartimento di Scienze Fisiche, Università degli Studi di Napoli Federico II, Via Cintia, Napoli 80126, Italy.
Nat Commun. 2012;3:989. doi: 10.1038/ncomms1996.
When an azobenzene-containing polymer film is exposed to non-uniform illumination, a light-induced mass migration process may be induced, leading to the formation of relief patterns on the polymer-free surface. Despite many years of research effort, several aspects of this phenomenon remain poorly understood. Here we report the appearance of spiral-shaped relief patterns on the polymer film under the illumination of focused Laguerre-Gauss beams with helical wavefronts and an optical vortex at their axis. The induced spiral reliefs are sensitive to the vortex topological charge and to the wavefront handedness. These findings are unexpected because the doughnut-shaped intensity profile of Laguerre-Gauss beams contains no information about the wavefront handedness. We propose a model that explains the main features of this phenomenon through the surface-mediated interference of the longitudinal and transverse components of the optical field. These results may find applications in optical nanolithography and optical-field nanoimaging.
当含有偶氮苯的聚合物薄膜受到非均匀照明时，可能会引发光致质量迁移过程，导致聚合物无表面形成浮雕图案。尽管经过多年的研究努力，但这一现象的几个方面仍未得到很好的理解。在这里，我们报道了在具有螺旋波前和光轴上的光学涡旋的聚焦拉盖尔-高斯光束照射下聚合物膜上出现螺旋形浮雕图案。所诱导的螺旋浮雕对涡旋拓扑电荷和波前手性敏感。这些发现是出乎意料的，因为拉盖尔-高斯光束的环形强度分布不包含有关波前手性的信息。我们提出了一个模型，通过光学场的纵向和横向分量的表面介导干涉来解释这一现象的主要特征。这些结果可能在光学纳米光刻和光场纳米成像中有应用。
