Peculiarities of spontaneous grating generation in light-sensitive waveguide layers during holographic grating formation |
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Authors: | L A Ageev V K Miloslavskii and K S Beloshenko |
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Institution: | 1.Kharkov National University, Kharkov, 61077, Ukraine ; |
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Abstract: | The generation of spontaneous (noise) gratings during the simultaneous formation of a holographic grating in thin (on the
order of the cutoff thickness of the TE0 waveguide mode) AgCl-Ag films by two laser beams with λ = 532 nm and polarization vectors that make an angle of 45° with
the plane of incidence have been studied. The electron microscopy images and diffraction patterns have revealed a significant
difference of the spontaneous-grating structure from the structure obtained under irradiation by one laser beam. The spontaneous
gratings have a significant spread in the directions of their wave vector, and the diffraction pattern (recorded using a probe
beam with λ = 337 nm) has the form of a bundle of diverging arcs that intersect at one point. This difference is caused by
self-diffraction from the holographic grating, which is responsible for the main diffraction peaks with odd orders, the growth
of spontaneous gratings because of the interference of the beams diffracted by the holographic grating with the waveguide
TE0 modes scattered in the film, and silver transport to the interference minima. The diffraction patterns are quantitatively
analyzed and the period of the new (formed under two-beam irradiation) spontaneous gratings is calculated. The calculation
results are in good agreement with the experimental data. |
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Keywords: | |
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