The Key Problems Of MultiLayer High Density Data Storage Using Femtosecond Laser

Three-dimensional optical data storage with femtosecond laser is a kind of technique for high and super-high capacity data storage.It's has been regarded as an important region for optical memory.Optical data storage based on one-beam two-photon excitation and microexplosion were investigated in theory and experiment with a femtosecond laser And the characterization of a variety of storage medium was studied in this paper.For reducing the information point size and increasing the storage capacity,the theory and experiment for optimizing the focal point of the laser was also investigated.This project was supported by National Nature Science Foundation of China (NO.50275140,No.50335050)and "863" project(MEMS 2003AA404050, No.2006AA04Z311).The main research results are listed as follows:First,the relationship between information point size and writing power and exposure time was analyzed for photochromic materials.The thermal stability and fatigue resistance were also studied.Multilayer data storage was realized in two kind of materials.Second,the characterization of photoluminescence and photobleaching was investigated in photobleaching materials.The relationship between information point and writing power and exposure time was also analyzed.The thermal stability and photoluminescence in long time were studied.Multilayer data storage was realized in two kind of materials.Third,the microexplosion threshold of PMMA was reduced through doping rare earth comlex or doping silver nanoparticles.The relationship between writing energy and microexplosion void size and the reading gray scale was investigated.The photoluminescence of microexplosion void in PMMA doped silver nanoparticles was also studied.Multilayer data storage was realized in this two kind of materials.Fourth,for increasing the storage capacity,reducing the information point size is a kind of method.Phase only pupil filter was investigated and designed.The influence of defocusing amount for the modulation of transverse focal point was investigated via the analyses of simple two zone 0-Ï€and 0-0.6Ï€superresolution elements. Three kinds of phase only plate for transverse,axial and three dimensional modulation were designed,and the change of focal point for Gauss beam was also studed.A four zone 0-Ï€filter was produced.The mismatching tolerance and testing tolerance were also analyzed.All these experimental results will be helpful to put three-dimensional optical data storage method based on two-photon excitation into practice.