We report the properties of a new polymer-guest photosensitive mixture based on two monomers with different
properties as basic components. The material has been characterized by recording holographic gratings using a low
power blue laser (405 nm) and a spectro-photometric technique to get the optical properties of the grating during and
after recording. The detected grating shows a very high sensitivity (of the order of 103 cm/J) and a surprising "antishrinkage" phenomenon (red-shift of the Bragg reflection grating wavelength).
In the last three decades several kinds of organic mixtures for holographic recording were developed in order to
achieve a new class of DVD-like optical memories for high-density optical data storage. The holographic materials
should satisfy the following requirements: high sensitivity to blue light, low losses, high spatial resolution and long term
stability. To this aim we developed new organic photosensitive mixtures based on only three components. We recorded
high spatial frequency reflection gratings up to 7400 lines/mm with blue laser light (405 nm) by using a conventional
holographic setup. We obtained a macro grating diffraction efficiency up to 67%, refractive index modulation over 0.01,
optical shrinkage < 2 % and overall losses ~5%. In order to characterize data-storage materials independently on the
experimental conditions, the sensitivity has been evaluated through the S parameter which takes into account the
diffraction efficiency, recording light intensity, exposure time and sample thickness. The amazing obtained values of S
>105 cm/J evidences a very fast recording process with a very low writing intensity (less than 20 mW/cm2) corresponding
to a recording energy density of few mJ/cm2. The performance of these materials have been also tested in the microholographic
geometry.
Holographic techniques allow the recording of homogeneous, high resolution, large-area light intensity patterns in photo
sensitive organic materials. The choice of proper experimental conditions easily permits the fabrication of 1D, 2D and
3D periodic and quasi-periodic structures. In this work we present a simple way to fabricate planar complex photonic
structures characterized by high dielectric contrast values. To this purpose we used polymer dispersed liquid crystals as
photosensitive material for the holographic recording, followed by the removal of the liquid crystal from the recorded
structures via a specific solvent, thus obtaining large area regular polymer-air patterns. The obtained structures have been
simulated, recorded in the substrates and optically characterized in planar light guided configurations. The relevant
optical properties have been analyzed by means of a theoretical approach formally derived from the dynamical theory of
x-ray diffraction. The presented experimental technique allows easy fabrication of optical integrated devices to be used
either as high sensitivity sensors or in the field of optical telecommunications.
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