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Continuous Spatial Tuning of Laser Emissions in a Full Visible Spectral Range
Department of Physics and Research Institute of Natural Science, Gyeongsang National University, Jinju 660-701, Korea
Department of Physics and Quantum Metamaterials Research Center, Ewha Womans University, Seoul 120-750, Korea
* Authors to whom correspondence should be addressed.
Received: 26 January 2011; in revised form: 4 March 2011 / Accepted: 18 March 2011 / Published: 21 March 2011
Abstract: In order to achieve a continuous tuning of laser emission, the authors designed and fabricated three types of cholesteric liquid crystal cells with pitch gradient, a wedge cell with positive slope, a wedge cell with negative slope, and a parallel cell. The length of the cholesteric liquid crystal pitch could be elongated up to 10 nm, allowing the lasing behavior of continuous or discontinuous spatial tuning determined by the boundary conditions of the cholesteric liquid crystal cell. In the wedge cell with positive slope, the authors demonstrated a continuous spatial laser tuning in the near full visible spectral range, with a tuning resolution less than 1 nm by pumping with only a single 355 nm laser beam. This continuous tuning behavior is due to the fact that the concentration of pitch gradient matches the fixed helical pitch determined by the cell thickness. This characteristic continuous spatial laser tuning could be confirmed again by pumping with a 532 nm laser beam, over 90 nm in the visible spectral range. The scheme of the spatial laser tuning in the wedge cell bearing a pitch gradient enabled a route to designing small-sized optical devices that allow for a wide tunability of single-mode laser emissions.
Keywords: tunable laser; photonic crystal; wedge cell; cholesteric liquid crystal laser
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Jeong, M.-Y.; Wu, J.W. Continuous Spatial Tuning of Laser Emissions in a Full Visible Spectral Range. Int. J. Mol. Sci. 2011, 12, 2007-2018.
Jeong M-Y, Wu JW. Continuous Spatial Tuning of Laser Emissions in a Full Visible Spectral Range. International Journal of Molecular Sciences. 2011; 12(3):2007-2018.
Jeong, Mi-Yun; Wu, Jeong Weon. 2011. "Continuous Spatial Tuning of Laser Emissions in a Full Visible Spectral Range." Int. J. Mol. Sci. 12, no. 3: 2007-2018.