Theoretical analysis of optical force density distribution inside subwavelength-diameter optical fibers**Project supported by the National Natural Science Foundation of China (Grant Nos. 11604230 and 11434017), the Guangdong Provincial Innovative and Entrepreneurial Research Team Program, China (Grant No. 2016ZT06C594), and the National Key Research and Development Program of China (Grant No. 2018YFA 0306200).

Abstract

We investigate the microscopic optical force density distributions respectively inside a subwavelength-diameter (SD) fiber with flat endface and inside one with oblique endface by using a finite-difference time-domain (FDTD) method. Optical force density distributions at the fiber endfaces can now be readily available. The complete knowledge of optical force density distributions not only reveal features regarding the microscopic near-field optomechanical interaction, but also provide straightforward explanations for the sideway deflections and other mechanical motions. Our results can provide a useful reference for better understanding the mechanical influence when light transports in a microscale or nanoscale structure and for developing future highly-sensitive optomechanical devices.