Electric and Magnetic Field Effect Studies on the Hologram Recording in Azobenzene Molecular Films

Various electrooptic and magnetooptic effects enable the electric and magnetic field control of the holographic information recording. They can become significant if the frequency of light irradiation is close enough to the absorption line of a material. In this paper, these effects are theoretically considered, and the influence of applied external electric (up to 17 kV/cm) as well as magnetic field (0.15T) is experimentally studied on the transmission holographic grating recording in azobenzene-based molecular films at 632.8 and 532 nm. Recording beam polarizations were s-s, p-p, L-L and L-R . Self-diffraction efficiency (SDE) exposure time dependences were measured with and without the applied fields, and maximum SDE values as well as recording energies corresponding to 0.017% SDE were determined. No effect of electric field was found within the measurement accuracy (1-5%). Some trend to recording efficiency increase by magnetic field was observed. This result is in the agreement with the theoretical analysis. Unfortunately, these results are within experimental errors (usually 15-24%).

DEVELOPMENT AND RESEARCH OF A PRECISION PIEZOELECTRIC Y-COORDINATE DRIVE FOR A CIRCULAR LASER WRITING SYSTEM

The paper presents the results of the development and research of a precision piezoelectric Y-coordinate drive for a circular laser writing system. The developed drive is designed to correct the direction of the linear scan path of the recording beam to align it with the center of rotation of the substrate.

Effect of light polarization on holographic recording in glassy azocompounds and chalcogenides

Light polarization effects on a holographic grating recording in a glassy chalcogenide a-As40S15Se45 film has been experimentally studied and compared with previously studied glassy molecular azobenzene film 8a at 633, using s − s,p − p, CE-1 and CE-2 circular-elliptic recording-beam polarizations (differing by light electric field rotation directions). The azocompound exhibited much higher self-diffraction efficiency (SDE) and diffraction efficiency whereas chalcogenide was more sensitive. Their recording efficiency polarization dependences also were different. SDE up to 45% was achieved in 8a with p − p and up to 2.6% in a-As40S15Se45 with CE-2 polarized recording beams. The polarization changes in the diffraction process were studied as well in these and other materials (11, 16, 19 and a-As2S3 film, LiTaO3:Fe crystal). It was found that light polarization changes in the process of diffraction from gratings recorded vectorially by s−p polarizations depended on chemical composition, wavelength, and exposure time. Vector gratings with SDE up to 25% were recorded in 8a, rotating a linear polarization by 90°. No light polarization changes were found in azobenzene 19 and chalcogenide films and in LiTaO3:Fe crystal, thus showing a vector recording of scalar holograms. The recording mechanisms in azocompounds and chalcogenides are discussed and compared.

Optical Behaviors of Novel Amorphous Ge – S – AgI Layers

The novel bulk glasses from the chalcohalide Ge-S-AgI system have been synthesized. From the as-prepared samples amorphous films have been deposited by vacuum thermal evaporation. The amorphous nature of the studied bulk and layered materials has been proved by Xray diffraction. The composition of the synthesized bulk chalcohalide glasses and corresponding amorphous thin films has been ascertained by means of Auger electron spectroscopy. The morphology and uniformity of the deposited layers have been investigated using scanning electron microscopy. The basic optical properties of the studied glassy films have been defined. Variations in the optical behaviors as a function of the composition have been derived. Experiments related to optical recording in the investigated Ge-S-AgI layers has been implemented. The diffraction efficiency as a function of various recording beam intensities has been obtained.

Optimal period for diffraction gratings recorded in polymer dispersed liquid crystals

New diffusion model of recording diffraction gratings in the media of PDLC is described in which besides diffusion of monomer molecules also diffusion of polymer molecules and non-locality of diffusion coefficient are taken into account. It lets us to explain why diffraction efficiency is low for low and high values of intensities of grating recording beam. With the considered model, we have theoretically got optimal period for grating recording.