Experimental Investigation of Laser Emission of Dye-Doped Cholesteric Liquid Crystals with a Cholesteric Reflector

Zhou, Ying; Huang, Yuhua; Rapaport, Alexandra; Bass, Michael; Wu, Shin‐Tson

doi:10.1080/15421400600656251

Cited by 2 publications

(2 citation statements)

References 17 publications

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“…The photonic stop band centered at λ=np, where p is the helical pitch and n the average refractive index: (n e +n o )/2. When the band edge overlaps the emission spectrum of the laser dye, and optical pumping is sufficiently strong, lasing of dye-doped CLC is observed at the band edges [2][3][4][5] . The lasing action can be controlled by varying the external factors such as electric field, temperature, and chemical species etc [6][7][8] .…”

Section: Introductionmentioning

confidence: 99%

Lasing from dye-doped planar cholesteric liquid crystal devices

Dai

Yan

et al. 2011

SPIE Proceedings

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The lasing action of dye doped cholesteric liquid crystal (CLC) cell was investigated in this work. A planar state was prepared by antiparallel rubbing process ITO glasses with polymide layer coating. The dye doped cholesteric liquid crystal mixture was used by mixing a laser dye DCM, a chiral agent CB15 and a nematic liquid crystal TEB30A. A second harmonic Q-switched Nd:YAG pulsed laser (λ=532nm) was used as the pumping source. A sharp peak was measured at 611 nm in the cell-normal direction and cell-plane direction after reaching threshold pump energy. The least full width of half maximum (FWHM) were about 10 nm and 12 nm. The optical structure of the device was investigated upon applied voltage. The results show that planar state of the CLCs is a prerequisite for the generation of lasing emission. So laser emission attributed to the photonic band gap (Bragg mode) in the cell-normal direction in which the helical axis exists. Due to the waveguide structure formed by the liquid crystal sandwiched between glass substrates (n e =1.522, n o =1.692＞n g =1.50), quasi-in-plane leaky lasing modes exist in the cell-plane direction.

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Section: Introductionmentioning

confidence: 99%

Lasing from dye-doped planar cholesteric liquid crystal devices

Dai

Yan

et al. 2011

SPIE Proceedings

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“…3 ͑solid red lines͒, to be less than 0.3 nm with a quality factor, defined as peak / FWHM, of about ϳ2000, which was comparable to other 1D lasing systems. 16 We used an effective medium approach to model the dye-doped, graded-layer structure ͑DGLS͒ sample and a transfer matrix to calculate the reflectance and transmittance. 14 We used a previously established calculation method 14 on a layered structure with graded spacing of 181-202 nm ͑top to bottom͒.…”

Section: -mentioning

confidence: 99%

Lasing from dye-doped photonic crystals with graded layers in dichromate gelatin emulsions

Kok

Lee

et al. 2008

Applied Physics Letters

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We report on optically pumped lasing from dye-doped, graded-spacing layer structures of dichromate gelatin emulsions fabricated using two-beam holographic interference. The graded layers exhibited deep and wide photonic band gaps. Multimode lasing with both a low threshold and a high quality factor was observed at the band edge of the photonic band gap. We modeled the emissions from the dye-doped graded layer system using a finite difference time domain technique and achieved good agreement with experimental results. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2907488͔ Photonic crystals exhibiting band gaps in which electromagnetic wave propagation is not possible have attracted much interest due to the potential that they can manipulate photons in optical microdevices.1 Among the many unique properties of photonic crystals, the control of the photonic density of states has a direct effect on the spontaneous emission of photons, which is an important capability in optoelectronics devices such as lasers, 2 light emitting diodes, 3 microwaveguides, 4 and many other promising photonic devices.5 It has been proposed that the enhancement of the spontaneous emissions in one-dimensional ͑1D͒ photonic crystals doped with gain materials is possible because of the localization at the band gaps and the high density of states at the band edges. 6 The realization of this enhancement was first demonstrated in GaAs light-emitting diodes sandwiched between stacks of 1D Bragg reflectors.7 Since then, lasing from dye-doped polymeric multilayers using distributed feedback and defect modes has been observed. 8,9 Recently, studies on band-edge and defect-mode lasing in dye-doped liquid crystals have attracted interest. 10 In these previous studies, equally spaced layers were employed in the systems. Lasing from 1D layers with gradually changing spacings ͑graded layers͒ is expected to be possible as well.One-dimensional stacks have been fabricated using a time-consuming layer-by-layer spin-coating method.7-9 Holographic lithography that employs the interference of multiple coherent beams is more efficient and has been used to fabricate two-dimensional as well as three-dimensional microstructures in photoresists.11 Furthermore, high-resolution holographic gelatin emulsions can be used to record the interference patterns.12,13 One advantage to using holographic gelatin emulsions is that the structure resulting from the interference is self-supporting inside the gelatin. It was further demonstrated that, with a volume hologram made from dichromate gelatin ͑DCG͒, highly efficient and wide-bandgap 1D layer structures could be achieved.14 The wide-bandgap results from the graded spacing of the 1D layers obtained by the differential swelling of the gelatin during the development process.14 Here, we show that lasing from dyedoped 1D graded layers in DCG holographic emulsions fabricated using two-beam interference is possible. Multimode lasing with both a low threshold and a high quality factor was observed at the band edge of the p...

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Experimental Investigation of Laser Emission of Dye-Doped Cholesteric Liquid Crystals with a Cholesteric Reflector

Cited by 2 publications

References 17 publications

Lasing from dye-doped planar cholesteric liquid crystal devices

Lasing from dye-doped planar cholesteric liquid crystal devices

Lasing from dye-doped photonic crystals with graded layers in dichromate gelatin emulsions

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