Interferometric analysis of reorientational nonlinear phenomena at 10.6 µm in a nematic liquid crystal

Year: 2003

Authors: Allaria E., Brugioni S., De Nicola S., Ferraro P., Grilli S., Meucci R.

Autors Affiliation: Istituto Nazionale di Ottica Applicata, Largo E. Fermi 6, 50125 Firenze, Italy; Istituto di Cibernetica \”E. Caianiello\” del Consiglio Nazionele delle Ricerche, Via Campi Flegrei 34, I 80078 Pozzuoli, Italy; Istituto per la Microelettronica e le Microtecnologie del Consiglio Nazionale delle Ricerche, Sezione di Napoli, Via Diocleziano 328, 80124 Napoli, Italy CNR-IMM

Abstract: We describe an infrared interferometric technique based on a two-dimensional spatial fringe analysis Fourier method for investigating the characteristic ring diffraction pattern generated by the self-phase-modulation effect induced in nematic liquid crystals (NLCs) by an infrared laser beam and for measuring the nonlinear refractive index of the NLCs. The experimental setup employs a Mach-Zehnder interferometer with a cw CO2 laser emitting at 10.6 mum and a pyroelectric optoelectronic sensor matrix to detect the modulated ring-pattern intensity distribution formed in the far field by a nematic E7 sample. A Fourier-transform-based analysis of the interference fringe pattern allows comparison of the measurements with the theoretical ring-pattern intensity distribution. We show that accurate determination of the nonlinear refractive index can be obtained by analyzing the two-dimensional phase distribution of the modulated ring pattern. (C) 2003 Optical Society of America.

Journal/Review: APPLIED OPTICS

Volume: 42 (24)      Pages from: 4827  to: 4834

KeyWords: Carbon dioxide lasers; Electromagnetic wave diffraction; Fourier transforms; Interferometry; Laser beams; Light interference; Nematic liquid crystals; Optical sensors; Phase modulation; Refractive index, Optical fringe patterns, Nonlinear optics
DOI: 10.1364/AO.42.004827

Citations: 3
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