Wavelength-multiplexing Holographic Storage Based On Selective Photo-oxidation Of Silver Nanoparticles

In the current highly information-oriented society,data storage with characteristics of high density,fast rate,and long life is desired.Holographic technology greatly improves the density and capacity of information storage.Multidimensional optical storage based on the multiplexing technology can pack more information within the same recording medium volume,which can meet the requirement of ultrahigh-capacity information storage.The major hurdle is the lack of a suitable recording medium with high resolution.Ag/TiO2 films have received much attention for their photosensitivity in wavelength and polarization.Moreover,Ag/TiO2 materials exhibit excellent photochromic properties and can be applied to high-density optical storage.In this paper,we carried out dual-wavelength holographic recording based on the Ag/TiO2 photochromic film.At the beginning,we carried out a preliminary exploration experiment.Firstly,the photochromic characteristics and holographic dynamics at 403.4 nm(blue-violet light)and at 532 nm(green light)were studied.The experimental results show that the photochromic rate under green light irradiation is faster than that of blue-violet light,which provides a basis for the selection of recording sequence in wavelength-multiplexing holography.Then,using the 403.4 nm and 532 nm lasers as pumping light source,we focused on the two kinds of recording procedures: sequential and simultaneous recording.The results show that,compared with the sequential recording mode,simultaneous recording procedure is more effective to the oxidative-dissolution of silver nanoparticles and obtain low-crosstalk spectral hole-burning.The multiplex-holographic dynamic curves with higher and more balanced diffraction efficiency were obtained.Moreover,in this recording mode,we observed more clearly multiplexed-holographic fringes with uniform contrast,and achieved the low-crosstalk multiplexed wavelength holographic storage.The experimental results can be explained by the Time-accumulation Effect during the diffusion and migration of silver ions.Taking the wavelength as a storage dimension,we also studied the photochromic properties under irradiation by the lasers at other wavelengths in this thesis,as well as the differential absorption spectra and the crosstalk under the co-irradiation of other wavelengths lights.By regulating the polarization and power ratio of excitation lights,low-crosstalk hole-burning was realized,which provides a new strategy for weakening crosstalk in multiwavelength holographic memory.The work provides important implications to multi-wavelength high-density storage and the fabrication of photonic devices with complex microstructures.