Browsing by Author "Luo, D."

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    Polarization-dependent circular Dammann grating made of azo-dye doped liquid crystals
    (Optical Society of America, 2011-05-19) Luo, D.; Sun, X. W.; Dai, H. T.; Demir, Hilmi Volkan
    A polarization-dependent circular Dammann grating (CDG) was generated from an azo-dye-doped liquid crystal (LC) cell. A simple multiexposure photo-alignment process was used to fabricate a binary phase LC CDG zone plane, which was composed of an odd zone with a twisted nematic LC structure and an even zone with a homogenous LC structure. A two-order CDG with equal-intensity rings was produced through a Fourier transform. The maximum zeroth and first diffraction orders of obtained CDG can be separately achieved by rotating the analyzer's polarization direction. The CDG using an azo-dye-doped LC cell can be used to generate diffractions by lasers in a broad wavelength range, hence expanding possible device applications.
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    Strongly linearly polarized low threshold lasing of all organic photonic quasicrystals
    (Nature Publishing Group, 2012-09-04) Luo, D.; Du, Q. G.; Dai, H. T.; Demir, Hilmi Volkan; Yang, H. Z.; Ji, W.; Sun, X. W.
    Lasing is obtained from a two-dimensional (2D) Penrose photonic quasicrystal made of a low index contrast material of holographic polymer dispersed liquid crystals (H-PDLCs) that enables a substantial reduction in the optical pumping threshold. This lasing architecture further allows for excellent linear polarization characteristics as well as wide directional dependence. The pumping threshold is fivefold lower than that obtained from the 2D defect-free photonic crystals fabricated under similar conditions. These properties make H-PDLC photonic quasicrystal promising for a new type of all organic miniature lasers.
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    Temperature effect on the lasing from a dye-doped two-dimensional hexagonal photonic crystal made of holographic polymer-dispersed liquid crystals
    (AIP Publishing, 2010-07-12) Luo, D.; Sun, X. W.; Dai, H. T.; Demir, Hilmi Volkan; Yang, H. Z.; Ji, W.
    Temperature dependent lasing was demonstrated in a dye-doped two-dimensional hexagonal photonic crystal made of holographic polymer-dispersed liquid crystals (LCs) along Gamma M direction in TE polarization. A redshift in lasing peaks was observed as the temperature increased from 25 to 45 degrees C. The downward movement of photonic band of TE polarization, majorly caused by the decrease in the anisotropy of LC droplets with the increase in temperature, is responsible for the redshift in lasing peaks.