非经典涡旋光束在高数值孔径系统中的传播特性  

Propagation properties of a non-canonical vortex beam in a high numerical aperture system

作　　者：李锦虹 庞晓炎 冯晨 LI Jinhong;PANG Xiaoyan;FENG Chen(School of Electronics and Information,Northwestern Polytechnical University,Xi’an 710072,China)

机构地区：[1]西北工业大学电子信息学院,陕西西安710072

出　　处：《西安电子科技大学学报》2020年第4期102-108,共7页Journal of Xidian University

基　　金：国家自然科学基金(11974281);西北工业大学硕士研究生创意创新种子基金(ZZ2019149)。

摘　　要：非经典涡旋是一种与经典涡旋具有相同拓扑荷数但是不同相位分布的光相位螺旋结构。基于理查德和沃尔夫矢量衍射理论,推导了在高数值孔径系统中线偏振非经典涡旋在焦点区域的表达式,并通过数值模拟研究了此光束在聚焦场的传播特性。研究中发现,横向焦移现象不仅存在于离轴(或轴上)涡旋的紧聚焦光场中,也存在于非经典涡旋的紧聚焦光场中,并且此两种横向焦移虽然表现形式一样,但是影响因素却截然不同。结果表明,由于横向焦移的存在,在非经典涡旋的相位分布因子和聚焦系统半孔径角满足一定的条件时,总场强分布图形可沿光轴方向顺时针旋转前进,同时场强最大值点也将从传播轴负半空间到正半空间旋转180°。研究结果为结构光场的调控提供新的方法,将在光镊等领域有潜在的应用。A non-canonical vortex is an optical helical phase structure with the same topological charge of a canonical vortex but different phase distributions.Based on the Richards&Wolf vectorial diffraction theory,the expression for the strongly focused,linearly polarized non-canonical vortex beam is derived,and its propagation properties are studied numerically in the focal region.It is that the transverse focal shift does not only occur in the strongly focused,off-axis(or on-axis)canonical vortex beams,but also can be seen in a strongly focused,non-canonical vortex beam.The transverse focal shift in these two fields have the same form,but the factors influencing them are quite different.It is also demonstrated that because of the transverse focal shift,if both the semi-aperture angle and the phase distribution factor meet a certain requirement,the total field intensity pattern in the focus region can rotate clockwise in the propagation direction,while the intensity maxima will also rotate 180°from the negative half space to the positive half space.The result will provide a new way for controlling the field distribution in structured fields,which may be applied in optical tweezers.

关 键 词：非经典涡旋 横向焦移 紧聚焦 

分 类 号：O436.1[机械工程—光学工程]