Full Optical Control of Holographic Gratings Realized in Composite Materials Containing Photosensitive Liquid Crystals

Abstract

We report on the characterization of an all optical switching effect that takes place when a UV light beam irradiates an azo-POLICRYPS diffraction grating. This high quality polymeric structure is utilized to confine and stabilize a well aligned nematic liquid crystal (NLC) film doped with a small percentage of azo-NLC molecules. The optical control of the grating diffraction efficiency is obtained by exploiting the photochemical phase transition between the nematic and the isotropic phases of the liquid crystal, based on the photoisomerization of the azobenzene guest molecules. The switch ON-OFF of the grating diffraction efficiency is triggered by a UV pump laser and is investigated by means of a low power red probe beam.

Light controlled bending of a holographic transmission phase grating

“…Photo-addressable holographic gratings have been studied for a long time. They are usually obtained by mixing azo-compounds with holographic polymer dispersed liquid crystal materials or with different nematic liquid crystals [11][12][13][14][15][16][17][18][19][20]. These mixtures are sensitive * Authors to whom any correspondence should be addressed.…”

Light-Induced Dynamic Holography

“…More recently, all optically addressable holographic gratings have been also widely studied. They are usually obtained in different ways and show peculiar properties, such as a fast oscillation frequency [9] or the possibility to be integrated into optical circuits as all-optical switches [10][11][12][13][14][15][16][17][18][19][20]. Holographic photomobile polymers (H-PMP) are photomobile materials on which holograms can be optically recorded.…”

Spectral, Morphological and Dynamical Analysis of a Holographic Grating Recorded in a Photo-Mobile Composite Polymer Mixture

“…All optically addressable holographic gratings have been studied for a long time. They are usually obtained by mixing azo-benzene-based molecules with holographic polymer dispersed liquid crystal (HPDLCs) materials or with different thermotropic nematic liquid crystals (NLCs) [1][2][3][4][5][6][7][8][9][10][11][12]. Those mixtures are sensitive to the polarization state of an impinging light, which affects the chemical configuration of the active azo-dye molecules present in the mixture.…”