The special shape of the optical disk tracking grooves is proposed. These tracking grooves are similar to the blazed
diffraction grating grooves. The grooves structure can be read by the standard optical disk reading equipment. The
multilayer optical disk with slant tracking grooves is proposed. These grooves have different planes and angles of
inclination for different data layers. This allows to direct the signals reflected from the different data layers to the
different photodetectors. The optical disk capacity increases due to excluding space between tracking grooves and due to
increasing the number of data layers. Sequential and parallel optical disk reading options are possible. The technique of
information pits arrangement is proposed for parallel reading of information from several data layers. For protecting of
the optical disk against its illegal use the disk is made partly recordable and an initialization procedure is performed at
the user's recording/reproducing device. During the initialization procedure identifying parameters of the user's device
are recorded onto recordable layer of the disk. Also, the unique combination of the bits pairs containing both information
prerecorded on the optical disk and information about the user's recording/reproducing device is remembered in the
special flash memory of the user's device.
The geometric-optical mechanism of wavefront reconstruction differs significantly from conventional holographic reconstruction. This regime can be realized for holograms containing only few periods of interference fringe structure. The geometric-optical reconstruction of the holograms recorded by femtosecond laser pulses in volume media was demonstrated in our previous works. The large thickness of the recording medium required for the effect observation is a serious obstacle for future development in this direction. In this work a way to surmount this obstacle by realizing the waveguide analog of the geometric-optical reconstruction process is presented. Holograms were recorded by 30-femtosecond laser pulses in 20-μm film of dichromated gelatin on the polished quartz substrate and reconstructed by the waveguide mode. Geometric-optical regime of waveguide hologram reconstruction was obtained: the direction of the reconstructed beam was observed to be constant as the reconstructing wavelength was varied within the hologram spectral selectivity band. The possibility of producing achromatic waveguide optical elements containing only few periods is discussed. The utilization of FIB (focused ion beam) nanotechnology for fabrication of these optical elements is proposed. Production of high aspect ratio periodic structures by FIB technology is demonstrated.
Holograms recorded in planar optical waveguides by 30 fs pulses from the second harmonic of a Ti:Sapphire laser (λ is about 400 nm) are investigated. The 20 μm thick films of dichromated gelatin (n<sub>2</sub> = 1 .54) deposited on a polished quartz substrate (n<sub>1</sub> = 1 .456) is used as a planar waveguide model. The recording pulses enter the planar waveguide through its upper surface. Reconstruction in the waveguide regime is investigated for the cases when λ ≅633 nm and λ lies between 1150 and 1250 nm.
The effect of geometric-optical wave front reconstruction is investigated. Femtosecond holograms, which demonstrate both diffraction and geometric-optical mechanisms of reconstruction, were obtained. The waveguide variant of the geometric-optical wavefront reconstruction and the ultrashort pulses temporal reconstruction are discussed.
A three-dimensional interference fringe structure containing only a small number of fringes is considered. The diffraction and geometrical-optical regimes of interaction of radiation with the structure are investigated.
The recording geometry and recording media for the method of achromatic wavefront reconstruction are discussed. The femtosecond recording on the thick slabs of dichromated gelatin and the samples of silver-containing porous glass was obtained. The applications of the method to ultrafast laser spectroscopy and to phase conjugation were suggested.
A new method of achromatic wavefront reconstruction by geometric-optical reflection of the reconstructing radiation from surfaces with constant phase difference between the object and reference waves is theoretically described and experimentally realized. Method's distinction from holographic one is discussed. Femtosecond laser pulses are used for recording in the experiment.