Optical reorientation and trapping of nematic liquid crystals leading to the formation of micrometer-sized domain

Anwar Usman*, Takayuki Uwada, Hiroshi Masuhara

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

We report on observation of optical reorientation of homogeneous nematic liquid crystals (LCs) thin slab of 4′-penthyl-4-cyanobiphenyl induced by a tightly focused near-infrared laser beam. We found that for laser beam with intensity higher than 56 MW/cm2 the optical reorientation unusually transforms to a new metastable domain, which grows with laser irradiation time up to a dimension much larger than that of the focal spot. The optically reoriented LCs with refractive index mismatch compared to the surroundings can act as a micrometer-sized ghost particle, leading to the generation of optical trapping and manipulation of the optically reoriented LCs. By using confocal Raman microspectroscopy, we show that the dichroic ratio in the confined focal volume changes upon the domain formation with an increase in the total Raman intensity, indicating that microscopic depolarization leading to deorientation or nematic → isotropic phase transition and possible microscopic densification takes place by the tightly focused laser beam.

Original languageEnglish
Pages (from-to)11906-11913
Number of pages8
JournalJournal of Physical Chemistry C
Volume115
Issue number24
DOIs
StatePublished - 23 Jun 2011

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