Abstract
In this paper, broadband Spectral Domain Interferometry provides single-shot optical characterization of dispersive thermotropic nematic liquid crystals. The proposed experimental setup enables measuring the chromatic dispersion, the extended Cauchy equation parameters knowing the optical index for one wavelength, and the thermo-optical coefficients to ascribe the dependence of the optical index with the inner temperature. The analysis is applied to the commonly known E 7 mixture and to M L C 2132 , whose chromatic properties are not referenced although the mixture is commercial, demonstrating the latter’s interest for electro-optical or thermo-optical applications of thick nematic liquid crystal cells.
Highlights
The remarkable optical properties of nematic liquid crystals (LC), e.g., tunable birefringence and transparency, induce a growing development of novel photonic applications based on light phase modulation
We propose exploiting a simple setup with single-shot acquisition for optical characterization of MLC2132 and comparison with E7
We have shown that common-path SDI performed with femtosecond pulses is suitable to achieve real-time tracking of the electro-optical changes in birefringence of nematics [3,11]
Summary
The remarkable optical properties of nematic liquid crystals (LC), e.g., tunable birefringence and transparency, induce a growing development of novel photonic applications based on light phase modulation. Electrically-addressed large cell gap nematics have attracted interests for terahertz phase shifters [5,6], high-resolution hyperspectral imaging [7,8,9,10], phase and group delay control of ultrashort pulses trains [11], tunable angular shearing in wedge-shaped cells [12] and terahertz vortex beam generators [13], just to cite a few. The combination of the LC layer thickness (180 μm) and its high birefringence enables achieving large phase-shift of several tens of radians Very recently, this thermo-optical mechanism resulted in an innovative phase shaper for multi-octave light sources [17]
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