Three-dimensional Optical Recording Research Articles

Structure and up-conversion luminescence in sol–gel derived Er 3+–Yb 3+ co-doped SiO 2:PbF 2 nano-glass–ceramics

Transparent oxyfluoride nano-glass–ceramics 90(SiO 2)10(PbF 2) co-doped with 0.3 Yb 3+ and 0.1 Er 3+ (mol%) have been prepared by thermal treatment of precursor sol–gel glasses. X-ray diffraction and high resolution transmission electron microscopy analysis pointed out a precipitation of cubic β-PbF 2 nanocrystals of certain diameter in nano-glass–ceramics varying from 10 to 20 nm depending on heat treatment conditions. The incorporation of Yb 3+ and Er 3+ dopants in these nanocrystals has been confirmed by signatures of luminescence spectroscopy. Up-conversion luminescence pumped at 980 nm has been detected. Colour tuneability of up-conversion luminescence varying pump power has been analyzed in terms of standard chromaticity diagram. This tuneability opens applications for up-conversion phosphors and three-dimensional optical recording.

Three-Dimensional Optical Recording in tert-Butoxycarbonyl-Protected Quinizarin Methacrylate Polymers

We report photoacid-induced nonerasable recording in tert-butoxycarbonyl-protected quinizarin methacrylate polymers for three-dimensional optical memory. 1 m/s-speed recording was achieved using an 800 nm femtosecond laser at an 80 MHz-repetition rate, without a postexposure bake after laser irradiation. Three-layer recording indicates that no optical damage during recording enables modulation of the Compact Disc type memory. The linewidth of recorded marks of 0.4 µm indicates a 49 Gbits/cm2 areal density when the numerical aperture is 1.35.

Cross talk in photochemical three-dimensional optical recording.

It is shown that the cross talk in three-dimensional optical photochemical recording results in ineffectiveness of single-photon recording. For two-photon recording for a given allowed cross-talk level there are optimal distances between spots that provide the maximum memory density. Estimations show that real restrictions here are connected with the reading of information.

Study of three-dimensional storage by parallel writing in PMMA with femtosecond laser pulses

Using a microlens array to focus an amplified femtosecond laser pulse inside a bulk PMMA(polymethyl methacrylate), optical breakdown occurs at each focus of the microlenses. By changing the positions of the foci,we realize the three-dimensional optical recording of high contrast bits at a speed of 20Mbit/s (with a 1kHz fs pulse laser ) in PMMA. Accordingly, modulation and readout of binary data have been presented. The diameter, focus length,and lens aberration in the microlenses are key factors which affect the recording speed and optical capacity based on this mechanism. Two kinds of effective ways to increase the capacity are discussed in this paper.

Demonstration of high-density three-dimensional storage in fused silica by femtosecond laser pulses

Three-dimensional optical recording of high contrast spherical bits (diameter<300 nm) at a density of 500 G/cm3 in fused silica using a Ti:sapphire femtosecond laser is demonstrated. Bits are optically read out using both a confocal and a phase-contrast scheme. The recording density for different materials and recording mechanisms are discussed.

Formation of multidomain structures in an optically bistable absorption system under the action of hyper-Gaussian light beams

It is shown that several longitudinal domains of high absorption are formed under certain conditions in an optically bistable element based on increasing absorption under the action of a hyper-Gaussian light beam. This is caused both by the transformation of the initial beam profile into a tubular distribution and by the diffraction of light by a nonuniform boundary of the region of high absorption. The analysis of dynamics showed the possibility of formation of quasi-stationary regions with high absorption, which exist during a certain time. These effects can lead to false data recording in three-dimensional optical recording systems.