Stokes-parameter analysis of the polarization of light transmitted through a chiral nematic liquid-crystal cell
A spectroscopic Stokes polarimeter is used to directly measure the linearly, circularly, and randomly polarized components of light obtained on transmission of unpolarized light through thick chiral nematic liquid-crystal cells in the stop band. The Stokes parameters are simulated to fit the experim...
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| Main Authors: | , , , , |
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| Format: | Article |
| Published: |
Optical Society of America
2005
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| Subjects: | |
| Online Access: | http://eprints.um.edu.my/12897/ http://www.opticsinfobase.org/josaa/abstract.cfm?uri=josaa-22-4-760 http://dx.doi.org/10.1364/JOSAA.22.000760 |
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| Summary: | A spectroscopic Stokes polarimeter is used to directly measure the linearly, circularly, and randomly polarized components of light obtained on transmission of unpolarized light through thick chiral nematic liquid-crystal cells in the stop band. The Stokes parameters are simulated to fit the experimental data by use of the Berreman 4 × 4 transfer matrix by means of the Jones and Stokes vectors and taking into account multiple reflections at the interfaces of the cell. Excellent agreement is obtained. The transmitted light through a commercial cell is mainly circularly polarized at normal incidence, but a significant linearly polarized component is also observed. The model shows that this results from refractive-index mismatching at the liquid-crystal–alignment-layer interface, but a small linearly polarized component remains even with optimized index matching. An improved device configuration incorporating random defects at the exit boundary of the liquid crystal gives a highly circularly polarized output with virtually no linear or unpolarized components. |
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