Theoretical Study On Optical Force In Micro/-nanofibers

The diameter of micro/-nanofiber is usually close to the wavelength of light,which makes it to exhibit many novel features,such as tight optical confinement,strong evanescent field,sensitive to weak light,outstanding mechanical properties,and small weight.Nowadays,with the rapid progresses in nanotechnology,there is an increasing demand for higher performance,denser integration,and lower power consumption,which has inspired great efforts for miniaturization of micro-nano photonic devices.As potential building blocks for miniaturization of photonic devices,micro/-nanofibers will certainly play an important role in the future.This article focuses on the optical force in the field of optomechanics.We used the finite-difference time-domain method to study the optical force on the micro-nanofiber endface in detail.The major results for this research is described as follows:1.We have studied the longitudinal optical force of circular micro-nanofibers and elliptical micro/-nanofibers.We have changed the radius of the circular micro/-nanofibers from 275 nm to 375 nm,and the long-to-minor axis ratio of the elliptical micro/-nanofibers from 1.1:1 to 1.5:1,and found that the longitudinal optical force of micro-nanofibers increases with the radius.Finally,we studied the influence of the mesh size near the end face.We have found that when the mesh size was less than 4 nm,the end face mutation value reached a numerical convergence.2.We have investigated the transverse optical force exerted on the end face of olive-shaped micro/-nanofibers and oblique-cut micro/-nanofibers.We have found that when the symmetry of the micro/-nano fiber is destroyed,it will be affected by the transverse optical force.The more thoroughly the symmetry is destroyed,the greater transverse optical force is.The lateral deflection of the micro/-nanofiber produced by transverse optical force cannot be ignored and has significance in practical application.Specifically,when the inclination angle is 80,the displacement of the 10-mm-length micro-nanofiber in the x direction can be 50?m.3.We have discussed the effects of the polarization and high-order modes on the tilted micro/-nanofibers.The simulation results show that when we change the polarization of the light mode,the optical force of the micro-nanofiber changes a little,and the polarization has no influence on the optical force of the micro/-nanofiber.When we choose a high-order mode,the behavior of transverse optical force of the tilt micro-nanofiber is interesting.The direction of transverse optical force will change with inclination angle,which means that we can control the direction of deflection by changing the inclination angle of the micro/-nano fiber.This discovery has a strong practical significance in the design of optomechanical devices.