Abstract: The surface quality of the titanium alloy determines the survival rate of the implant directly. For the shortcomings of the traditional surface treatment method, this paper proposed a surface treatment method based on time domain finite difference method, which used a gold nanoparticle with diameter of 200 nm on alloy titanium alloy. The influence of laser parameters on the field distribution on titanium alloy surface were studied. The results show that the near-field enhancement region excited by 200 nm gold nanoparticles is annular, and the enhancement ratio is more than 6500 times. By increasing the angle of the incident light, the enhancement ratio can be further improved, while the background refractive index of the gold nanoparticles has a small effect on the enhancement effect, which indicated that this method can be surface treated in a variety of media.

Key words: nano-particles, surface treatment, laser micro-nano processing, noble metals