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Continuous spatial tuning of laser emissions in a full visible spectral range.

Jeong MY, Wu JW - Int J Mol Sci (2011)

Bottom Line: 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.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.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Research Institute of Natural Science, Gyeongsang National University, Jinju 660-701, Korea.

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.

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(a) Laser lines of the wedge cells as a function of spatial position for each WL-, WM-, and WS-cell, respectively; (b) Photographs of red, green and blue lasing.
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f4-ijms-12-02007: (a) Laser lines of the wedge cells as a function of spatial position for each WL-, WM-, and WS-cell, respectively; (b) Photographs of red, green and blue lasing.

Mentions: Figure 4 shows the laser lines of the wedge cells with positive slope as a function of spatial position with the inset of the lasing photographs for each WL-, WM-, and WS-cell, respectively. In the WL-cell (DCM and LDS698 dyes were added), a continuous tuning of the laser was achieved over a range of 97 nm, from 580.69 nm to 676.91 nm, with an accuracy of Δλ ≈ 1 nm, by a 100 μm spatial movement of the cell in the x-direction (Figure 4a). This continuous tuning behavior is due to the fact that the concentration of pitch gradient fit with the helical pitch determined by the cell thickness (see Figure 1a).


Continuous spatial tuning of laser emissions in a full visible spectral range.

Jeong MY, Wu JW - Int J Mol Sci (2011)

(a) Laser lines of the wedge cells as a function of spatial position for each WL-, WM-, and WS-cell, respectively; (b) Photographs of red, green and blue lasing.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3111647&req=5

f4-ijms-12-02007: (a) Laser lines of the wedge cells as a function of spatial position for each WL-, WM-, and WS-cell, respectively; (b) Photographs of red, green and blue lasing.
Mentions: Figure 4 shows the laser lines of the wedge cells with positive slope as a function of spatial position with the inset of the lasing photographs for each WL-, WM-, and WS-cell, respectively. In the WL-cell (DCM and LDS698 dyes were added), a continuous tuning of the laser was achieved over a range of 97 nm, from 580.69 nm to 676.91 nm, with an accuracy of Δλ ≈ 1 nm, by a 100 μm spatial movement of the cell in the x-direction (Figure 4a). This continuous tuning behavior is due to the fact that the concentration of pitch gradient fit with the helical pitch determined by the cell thickness (see Figure 1a).

Bottom Line: 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.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.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Research Institute of Natural Science, Gyeongsang National University, Jinju 660-701, Korea.

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.

Show MeSH