Blue-Phase Liquid Crystal Acts as Laser
Researchers at Kent State University in Ohio and Universidad Autonoma Metropolitana in Mexico City reported in the October issue of Nature Materials that they have observed lasing in optically pumped blue-phase liquid crystal. The effect, which they attribute to optical feedback by internal Bragg reflection and to coupling of the orthogonal modes by Bragg diffraction, also may have applications in the fabrication of waveguides, switches and sensors.
The scientists investigated the nematic liquid crystal E48 at 24.4 °C, to which they added the chiral dopant CB15 and DCM dye and which they sandwiched between ITO-coated glass plates. They pumped the samples with 7.5-ns pulses of 532-nm light from an Nd:YAG laser, and observed laser emission at slightly different wavelengths centered around 617 nm from crystals in the (100), (010) and (001) orientations.
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