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Measurements of piezooptic coefficients π14 and π25 in Pb5Ge3O11 crystals using torsion induced optical vortex 
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Vasylkiv Yu., Skab I. and Vlokh R.

We show how a singularity of optical field can be used for determination of piezooptic coefficient of crystals under their torsion, in particular in the situation when the natural optical activity makes direct polarimetric experiments too complicated. Experimental studies of an optical vortex appearing under torsion of lead germanate crystals have enabled us to determine so-called non-principal coefficients (π14 and π25). A relationship between the spin angular momentum of light beam and the piezooptic coefficients has been derived.

Keywords: : torsion stress, optical vortex, spin angular momentum, piezooptic coefficients, lead germanate crystals

PACS: 78.20.Hp, 78.20.Ek, 74.25.Uv, 42.50.Tx
UDC: 535.551
Ukr. J. Phys. Opt. 12 101-108 
doi: 10.3116/16091833/12/2/101/2011
Received: 05.04.2011

Анотація. В роботі показано, яким чином можна використати сингулярності оптичного поля для вимірювання п’єзооптичних коефіцієнтів при крученні кристалів, за умови, що природна оптична активність створює перешкоди прямим поляриметричним дослідженням. Експериментальне дослідження оптичного вихору, який виникав при крученні кристалів германату свинцю дозволило визначити, так звані, неголовні пєзооптичні коефіцієнти (π14 та π25). Отримано співвідношення між спіновим кутовим моментом пучка і 
пєзооптичними коефіцієнтами.
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