Diffraction Efficiency and Selectivity of Polarization Holographic Recording

Biphotonic holographic gratings in azobenzene polyesters: Surface relief phenomena and polarization effects

“…This strong selectivity with respect to the polarization of the reconstructing beam is typical of these kinds of polarization gratings. 16 Figure 4 shows the evolution of the I 1,ϩ1 order of diffraction. As this is superimposed to the zero order of the I 2 beam, the detector is screened until the I 2 beam is blocked at tϭ1350 s. As with the intensity gratings, an increase of the diffracted intensity with time is observed in the polarization gratings when the film is either illuminated with a single He-Ne beam or kept in darkness for several hours.…”

High diffraction efficiency polarization gratings recorded by biphotonic holography in an azobenzene liquid crystalline polyester

“…High diffraction efficiencies ͑up to 80%͒ 2 have been obtained in gratings generated with a polarization modulated pattern. 7 The appearance of periodic surface relief structures associated with the optical recording has also been observed in these films. 8,9 From a technological point of view it is of interest to shift the recording wavelength to the red region, where an inexpensive diode laser could be used.…”

“…In this setup the intensity is constant over the entire area of the film, but the resultant linear polarization is periodically modulated. 7 The jth diffracted order arising from the incident beam I i is denoted by I i, j . Thus I 1,ϩ1 denotes the order ϩ1 arising from I 1 .…”

“…7 The circularly polarized I 1 beam from the He-Ne laser was allowed to fall upon the grating after the film had reached its efficiency saturation value. We did not observe, at this stage, any influence of the He-Ne light on the behavior of the grating.…”

Polarization Holographic Gratings Formed on Polymer Dispersed Liquid Crystals

“…Because of their optically active properties, polarization holographic gratings are promising in the production of high-function optical devices such as lights modulators, valves, polarization multiplexers and demultiplexers, polarized radiation splitters (Bunning et al, 2000;Cipparrone et al, 2000;Cipparrone et al, 2001a;Habraken et al, 1995;Ono et al, 2005;Wu et al, 2001;Yu et al, 2002). Such gratings are recorded on polarization-sensitive materials: photo-refractive crystals (Sturman et al, 1996), «guest-host» systems (Khoo, 1991;Slussarenko et al, 1997;Nikolova & Todorov, 1984), azopolymers (Naydenova et al, 1998;Labarthet & Rochon, 1999). The reports about the record of the polarization gratings in liquid-crystal composites (LC-composites) which do not contain azodyers, are comparatively recent (Cipparrone et al, 2001a;Mazzulla et al, 2004).…”