Theoretical analysis of optical force density distribution inside subwavelength-diameter optical fibers

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.