Investigation Of Particle Movement In Thermal Field And The Photonic Crystal Nanocavity

This dissertation follows the lead of Electrorheological (ER) fluid effect, using the thermal-electric analog technical to analyze the movement of the particles in the thermal gradient system. Particles will be polarized in the constant thermal gradient condition, as the dielectric particles will be polarized in the electric field (ER effect). After calculating the strength of the polarization of the particles in thermal gradient system, it is possible to forecast the movement tendency with the energy distribution of the particles. We set up this system in COMSOL, using two different temperature plates to form a constant thermal gradient field, and calculating the energy of the particles in this field to estimate the movement of the particles. The result shows that particles have the tendency to for chains. According to the calculation result, different material particles are used in this thermal gradient system and its movement rules are observed.Except the observation of particles movement in thermal system, we have discussed a photonic crystal nanocavity structure to get the optical force. Ashkin first use the highly concentrated laser forming a optical trap to manipulate the dielectric particles, people devote great favor to design the optical force device, up to now, the optical forces that produced by these devices are not strong enough to manipulate the macro-scale objects, and that it still has not an effect way to adjust the optical force intensity. We use the finite-different time-domain (FDTD) method to simulate an optical force system, which the photonic crystal cavity is coupling with the nanorod, when the system is equilibrium; the intensity of the interaction force will reach uN, moreover, we designed the quantum dot (QD) layers which can modulate the evanescence electric field of the cavity surface, to turn up the optical force.