scholarly journals Waveguide amplification of dye fluorescece in NLC

2018 ◽  
Vol 10 (4) ◽  
pp. 106
Author(s):  
Nikolay M. Shtykov ◽  
Serguei P. Palto ◽  
Boris A. Umanskii ◽  
Dmitry O. Rybakov ◽  
Ivan V. Simdyankin
Keyword(s):  
Liquid Crystal ◽  
Light Propagation ◽  
Optical Pumping ◽  
Periodic Structures ◽  
Wave Theory ◽  
Distributed Feedback ◽  
Research Network ◽  
Liquid Crystal Layer ◽  
Planar Layer ◽  
Uniform Liquid

The amplification of spontaneous fluorescence in a planar layer of a nematic liquid crystal doped with a DCM dye is experimentally studied in a waveguide mode of light propagation. The optical pumping threshold of the superfluorescence is 0.65 MW/cm2. The gain value reaches 0.0014 μm-1 at a pumping intensity of 1.38 MW/cm2. Full Text: PDF ReferencesLiquid Crystal Microlasers, Eds. L. M. Blinov, R. Bartolino (Kerala India, Transworld Research Network 2010). DirectLink H. Kogelnik, C. V. Shank, "Coupled‐Wave Theory of Distributed Feedback Lasers", J. Appl. Phys. 43, 2327 (1972). CrossRef I. P. Il'chishin, E. A. Tihonov, V. G. Tishchenko, M. T. Shpak, "Generation of a tunable radiation by impurity cholesteric liquid crystals", JETP Lett. 32, 25 (1980). DirectLink A. Yariv, M. Nakamura, "Periodic structures for integrated optics", IEEE Quant. Electr. 13, 233 (1977). CrossRef N. M. Shtykov, M. I. Barnik, L. M. Blinov B. A. Umanskii, S, P. Palto, "Amplification of the emission of a liquid-crystal microlaser by means of a uniform liquid-crystal layer", JETP Lett. 85, 602 (2007). CrossRef

Amplification of the emission of a liquid-crystal microlaser by means of a uniform liquid-crystal layer

JETP Letters ◽  
2007 ◽  
Vol 85 (12) ◽  
pp. 602-604 ◽  
Author(s):  
N. M. Shtykov ◽  
M. I. Barnik ◽  
L. M. Blinov ◽  
B. A. Umanskii ◽  
S. P. Palto
Keyword(s):  
Liquid Crystal ◽  
Crystal Layer ◽  
Liquid Crystal Layer ◽  
Uniform Liquid

scholarly journals Optofluidic Platform Based on Liquid Crystals in X-Cut Lithium Niobate: Thresholdless All-Optical Response

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 908
Author(s):  
Fabrizio Ciciulla ◽  
Annamaria Zaltron ◽  
Riccardo Zamboni ◽  
Cinzia Sada ◽  
Francesco Simoni ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Light Intensity ◽  
Lithium Niobate ◽  
Photovoltaic Effect ◽  
Optical Control ◽  
Crystal Layer ◽  
Liquid Crystal Layer ◽  
Threshold Behaviour ◽  
All Optical

In this study, we present a new configuration of the recently reported optofluidic platform exploiting liquid crystals reorientation in lithium niobate channels. In order to avoid the threshold behaviour observed in the optical control of the device, we propose microchannels realized in a x-cut crystal closed by a z-cut crystal on the top. In this way, the light-induced photovoltaic field is not uniform inside the liquid crystal layer and therefore the conditions for a thresholdless reorientation are realized. We performed simulations of the photovoltaic effect based on the well assessed model for Lithium Niobate, showing that not uniform orientation and value of the field should be expected inside the microchannel. In agreement with the re-orientational properties of nematic liquid crystals, experimental data confirm the expected thresholdless behaviour. The observed liquid crystal response exhibits two different regimes and the response time shows an unusual dependence on light intensity, both features indicating the presence of additional photo-induced fields appearing above a light intensity of 107 W/m2.

Light propagation mechanism switching in a liquid crystal infiltrated microstructured polymer optical fibre

2015 ◽  
Vol 23 (4) ◽  
Author(s):  
K.A. Rutkowska ◽  
K. Milenko ◽  
O. Chojnowska ◽  
R. Dąbrowski ◽  
T.R. Woliński
Keyword(s):  
Liquid Crystal ◽  
Optical Fibre ◽  
Total Internal Reflection ◽  
Light Propagation ◽  
Propagation Mechanism ◽  
External Temperature ◽  
Air Channels ◽  
Propagation Properties ◽  
Infiltration Method ◽  
Light Guidance

AbstractIn this work studies on propagation properties of a microstructured polymer optical fibre infiltrated with a nematic liquid crystal are presented. Specifically, the influence of an infiltration method on the LC molecular alignment inside fibre air-channels and, thus, on light guidance is discussed. Switching between propagation mechanisms, namely the transition from modified total internal reflection (mTIR) to the photonic bandgap effect obtained by varying external temperature is also demonstrated.

scholarly journals Dissipative structures induced by photoisomerization in a dye-doped nematic liquid crystal layer

2018 ◽  
Vol 376 (2135) ◽  
pp. 20170382 ◽  
Author(s):  
I. Andrade-Silva ◽  
U. Bortolozzo ◽  
C. Castillo-Pinto ◽  
M. G. Clerc ◽  
G. González-Cortés ◽  
...  
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Dissipative Structures ◽  
Input Power ◽  
Isotropic Phase ◽  
Crystal Layer ◽  
Liquid Crystal Layer ◽  
Nematic Liquid Crystal Layer ◽  
Interface Propagation

Order–disorder phase transitions driven by temperature or light in soft matter materials exhibit complex dissipative structures. Here, we investigate the spatio-temporal phenomena induced by light in a dye-doped nematic liquid crystal layer. Experimentally, for planar anchoring of the nematic layer and high enough input power, photoisomerization processes induce a nematic–isotropic phase transition mediated by interface propagation between the two phases. In the case of a twisted nematic layer and for intermediate input power, the light induces a spatially modulated phase, which exhibits stripe patterns. The pattern originates as an instability mediated by interface propagation between the modulated and the homogeneous nematic states. Theoretically, the phase transition, emergence of stripe patterns and front dynamics are described on the basis of a proposed model for the dopant concentration coupled with the nematic order parameter. Numerical simulations show quite a fair agreement with the experimental observations. This article is part of the theme issue ‘Dissipative structures in matter out of equilibrium: from chemistry, photonics and biology (part 2)’.

Anchoring Induced by Porous Substrate on a Liquid Crystal Layer

1994 ◽  
Vol 239 (1) ◽  
pp. 257-261 ◽  
Author(s):  
Francesco Simoni ◽  
Ferdinando Basile ◽  
Francesco Bloisi ◽  
Luciano Vicari ◽  
Fouad Aliev
Keyword(s):  
Liquid Crystal ◽  
Crystal Layer ◽  
Porous Substrate ◽  
Liquid Crystal Layer

scholarly journals Self-Aligned Emission of Distributed Feedback Lasers on Optical Fiber Sidewall

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2381
Author(s):  
Tianrui Zhai ◽  
Xiaojie Ma ◽  
Liang Han ◽  
Shuai Zhang ◽  
Kun Ge ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Coupling Effect ◽  
Wave Theory ◽  
Dip Coating ◽  
Distributed Feedback ◽  
Power Delivery ◽  
Fiber Axis ◽  
Fiber Waveguide ◽  
Multi Wavelength ◽  
Dfb Laser

This article assembles a distributed feedback (DFB) cavity on the sidewalls of the optical fiber by using very simple fabrication techniques including two-beam interference lithography and dip-coating. The DFB laser structure comprises graduated gratings on the optical fiber sidewalls which are covered with a layer of colloidal quantum dots. Directional DFB lasing is observed from the fiber facet due to the coupling effect between the grating and the optical fiber. The directional lasing from the optical fiber facet exhibits a small solid divergence angle as compared to the conventional laser. It can be attributed to the two-dimensional light confinement in the fiber waveguide. An analytical approach based on the Bragg condition and the coupled-wave theory was developed to explain the characteristics of the laser device. The intensity of the output coupled laser is tuned by the coupling coefficient, which is determined by the angle between the grating vector and the fiber axis. These results afford opportunities to integrate different DFB lasers on the same optical fiber sidewall, achieving multi-wavelength self-aligned DFB lasers for a directional emission. The proposed technique may provide an alternative to integrating DFB lasers for applications in networking, optical sensing, and power delivery.

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