Femtosecond Laser Induced Microstructures In Materials And Potential Application On Optical Storage

The 21st century is an era of big data and information.The explosion of information storage and dissemination poses new challenges to human society.Throughout the world,a large amount of data is generated in the form of video,audio,pictures,documents and newspapers every day.In particular,the development of the mobile Internet promotes the generation and dissemination of information.Currently,all of these data are stored with magnetic storage,optical storage,and IC solid state memory successfully by improving storage capacity with minifying recording elements.However,the storage capacity of all these two-dimensional storage methods is approaching its physical limit.Multi-dimensional storage is a new direction for the development of data storage,which increases the storage capacity by more than an order of magnitude.Due to various physicochemical changes that can be used for multi-dimensional recording during the light-matter interaction,multi-dimensional optical storage has drawn much attention in recent years.The interactions,multiphoton ionization process,tunnel ionization and avalanche ionization,between femtosecond laser and various transparent materials are usually based on nonlinear processes due to its ultrashort pulse duration and ultrahigh energy density,so as to realize the micro-structure change of transparent medium spatially and selectively.In the deepening research,femtosecond laser has become an important tool for three-dimensional modification of the physical properties of the material.In this paper,we utilized the femtosecond laser to induce diverse functional microstructures in different materials.We also investigated the microstructures and discussed the mechanism,and finally explored the potential application of different microstructures in the field of optical storage.The details are described as follows:?1?Cr³⁺ion-doped aluminosilicate glass was prepared by a conventional melt-quenching technique.After irradiation by high-frequency femtosecond laser,the precipitation of ZnAl₂O₄ crystals was successfully achieved.In addition,the Cr³⁺in the glass is embedded in the induced crystals,and the broadband luminescence due to Cr³⁺transition is observed in the irradiated area.Finally,we analyzed the potential for three-dimensional optical storage using this technology.?2?The ZnO-TeO₂-P₂O₅ glass was irradiated by femtosecond laser with different frequency to realize controllable precipitation from clusters to nanoparticles.Raman imaging was used to characterize the distribution of clusters and nanoparticles in the induced microstructure.The mechanism was discussed.Based on the near-infrared fluorescence of the clusters,the feasibility for three-dimensional optical storage was further demonstrated.?3?Silver-doped phosphate glass was irradiated by 1 kHz femtosecond laser.Based on the change of valence and fluorescence of silver ions,this technique is potential for ultra-fast optical storage.The inter-layer crosstalk,capacity,and thermal stability of the information are further explored,and the lifetime of the storage information was calculated theoretically.In the drawn conclusions,we demonstrated its application in three-dimensional storage,and we got a high signal-noise ratio and stability.?4?The PVA fiber membranes doped with oriented gold nanorods were prepared by electrospinning technology,and the correlation coefficients of readout signal with different aspect ratios under polarized laser light were further explored.A multi-layered read was tried to lay the foundation for the further development of multidimensional optical storage based on oriented gold nanorods.