Experimental Study Of Femtosecond Laser Repairing Defects In Glass Material Induced By Ion Implantation

Metal ion implantation in insulators, with a high ability in controlling the implantation parameters, is a promising doping method to fabricate nonlinear optical devices such as waveguides and optical switches since it can form a layer embedded with metal nanoparticles a certain distance below the surface of the transparent materials. But this method inevitably induces trains of defects in matrix when the incidence ions intruding into the implanted materials. In some cases, these defects should be annihilated to eliminate when a crystalline construction is needed. In this paper, we employed a new method to achieve defect repairing using the low-energy femtosecond laser based on nonlinear absorption and electron excitation process. The work in this paper includes:(1) The process of the ion implantation and the characterization of defects is simulated and calculated by the SRIM(Stopping and Range of Ions in Matter). The results of the simulation concludes the distribution of the Cu ions, the 2D mapping of the defects and the ions in the target, the recoil atoms in the target and the ionization and recoil energy distribution of the intruding Cu ions. The simulation results demonstrate the formation, types and the characterization of the ions and defects in the target, thus provides us a guide of the ion implantation and laser irradiation experiments.(2) Building the femtosecond laser irradiation experimental set-up: a femtosecond laser with a pulse width of 35 fs was used for the experiment. The irradiation system used varies optical and electrical devices to achieve high energy control accuracy. The specimen was screwed onto a translation stage to achieve high spatial resolution of laser irradiation. The main idea of programming of the translation stage is shown in this paper.(3) Femtosecond laser’s repairing effects of the matrix defects in fused silica induced by the Cu ion implantation has been studied by ion implantation experiment, irradiation experiment and a series of characterization. The absorption rate was tested by an ultraviolet-visual spectrophotometer(Lambda 35) and the information of matrix defects was characterize by the Raman spectrometer. The topography of the surface was observed by atomic force microscope(AFM).The results showed that when we control the nonlinear absorption and electron excitation process through the laser’s energy, the atoms can gain suitable energy to annihilate the matrix defects. Because the repairing process was based on the excitation of the electrons and carriers in the atom by the femtosecond laser, it achieves high effectiveness, convenience and spatial selectivity. Compared to other annealing methods, this approach does not cause melting or ablation and needs no simultaneous irradiation. So the repairing method has a potential value in area of fabricating optical switches, waveguides and other nonlinear optical devices.