Two-photon Polymerization Micro-fabrication By Femtosecond Laser

The two-photon micro-fabrication technology employs the two photon absorption locally induced between the material and the femtosecond laser to achieve 3D shaping through point to point scan and it is a new micro-fabrication technology. Recently, many micro-devices such as micro-lens, micro-gears, micro-cow, waveguides, micro-springs, 3D-photonic crystal, Fresnel zone plates have been fabricated by two-photon polymerization.Great interest is focused on femtosecond laser micro-fabrication due to the ultra - short time scale and ultra - high peak power density characteristics of the femtosecond lasers. The rate of two photon excitation is proportional to the squared intensity of the incident light. Very high resolution and accuracy can be achieved when working with rigid materials and liquid resin. The two-photon micro-fabrication technology will have wide application in many fields such as micro-fabrication, microelectronics, light communications and biology.Firstly, in this paper, we reviews the significance, principle, characterization of two photon micro-fabrication technology and the development process of the femtosecond laser.Secondly, we builds 3D-microfabrication experimental system which consists of a laser system, a microscope system, a real-time detection system and a 3D-movement system, etc. The precision of micro-machining reaches a level down to 200nm line-width.Thirdly, Optimization of process parameters is an important condition of two photon micro-fabrication. After analyzed, the exciting laser intensity, the coverage rate and the numerical aperture of objectives are selected for experimental research. Using the two photon micro-fabrication system we built, the experimental results under the different conditions varying one process parameter while fixing the other process parameters are compared and the effect of the parameter on the processing quality is discussed. Some experimental results after the optimization of the process parameters are given.At last, using the two photon micro-fabrication system, we succeed in fabricating some micro-devices such as Fresnel zone plates, gratings, lattice, 3D-photonic crystal and so on. Furthermore, we manage to test the optical property of the Fresnel zone plates with a microscope. Experimental results demonstrate this technique is very flexible.