Relationship between liquid crystal layer thickness and variable-focusing characteristics of an ultrasound liquid crystal lens

2022 ◽  
Author(s):  
Takahiro Iwase ◽  
Jessica Onaka ◽  
Akira Emoto ◽  
Daisuke KOYAMA ◽  
Mami Matsukawa
Keyword(s):  
Liquid Crystal ◽  
Layer Thickness ◽  
Focal Length ◽  
Optical Microscope ◽  
The Other ◽  
Driving Voltage ◽  
Crystal Layer ◽  
Liquid Crystal Layer ◽  
Variable Focus ◽  
Liquid Crystal Lens

Abstract The effect of the liquid crystal (LC) layer thickness on the optical characteristics of an ultrasound LC lens was explored. Three LC lenses with differing LC layer thicknesses (100, 200, and 300 µm) were fabricated, and the optical focal lengths were measured by an optical microscope with a varying driving voltage. For the lens with a 200-µm-thick LC layer, a larger change in the focal length was observed for a smaller driving voltage compared with that of the other two lenses, indicating that the LC layer thickness is appropriate for a variable-focus lens.

scholarly journals Response Improvement of Liquid Crystal-Loaded NRD Waveguide Type Terahertz Variable Phase Shifter

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 307 ◽  
Author(s):  
Trong Nghia Lang ◽  
Van Bao Bui ◽  
Yo Inoue ◽  
Hiroshi Moritake
Keyword(s):  
Liquid Crystal ◽  
Response Time ◽  
Phase Change ◽  
Decay Time ◽  
Phase Shifter ◽  
Dielectric Anisotropy ◽  
Driving Voltage ◽  
Crystal Layer ◽  
Liquid Crystal Layer ◽  
Waveguide Type

Liquid crystals, which have high dielectric anisotropy even in the terahertz region and are easily controllable for dielectric permittivity by applying an electric field, have become increasingly attractive in recent years. The non-radiative dielectric (NRD) waveguide has a structure in which a dielectric line is sandwiched between two metal plates and by replacing the dielectric part with liquid crystal, a low loss liquid crystal-loaded NRD waveguide type terahertz phase shifter can be obtained. However, since the thickness of the liquid crystal layer is several hundred micrometers, it has a response time of as long as several hundred seconds when the driving voltage is removed. It is necessary to devise improvements for practical application. By inserting two polyethylene terephthalate (PET) films and reducing the thickness of the liquid crystal layer, the decay time was improved well, but the phase change was significantly reduced. In this study, we report improving both decay time and phase change with aligned nanofiber/liquid crystal complex. In addition, we demonstrate liquid crystal-load phase shifter, which has 360° phase change and the response time below one second.

scholarly journals Intracavity measurement of liquid crystal layer thickness by wavelength tuning of an external cavity laser diode

2005 ◽  
Vol 13 (20) ◽  
pp. 7905 ◽  
Author(s):  
Yu-Ping Lan ◽  
Yea-Feng Lin ◽  
Yu-Tai Li ◽  
Ru-Pin Pan ◽  
Chao-Kuei Lee ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Layer Thickness ◽  
Laser Diode ◽  
External Cavity ◽  
Wavelength Tuning ◽  
Crystal Layer ◽  
Liquid Crystal Layer ◽  
External Cavity Laser ◽  
Cavity Laser

Influence of the alignment layer and the liquid crystal layer thickness on the characteristics of electrically controlled optical modulators

2009 ◽  
Vol 35 (6) ◽  
pp. 498-500 ◽  
Author(s):  
V. N. Vasil’ev ◽  
E. A. Konshina ◽  
D. S. Kostomarov ◽  
M. A. Fedorov ◽  
L. P. Amosova ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Layer Thickness ◽  
Crystal Layer ◽  
Liquid Crystal Layer ◽  
Optical Modulators ◽  
Alignment Layer

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.

Effective Voltage Control of Liquid Crystal Lens for Rapid Focal Length Change

2021 ◽  
Author(s):  
Tsugumi Fukui ◽  
Sota Shimizu ◽  
Keigo Muryobayashi ◽  
Marenori Kawamura ◽  
Susumu Sato ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Focal Length ◽  
Voltage Control ◽  
Length Change ◽  
Effective Voltage ◽  
Liquid Crystal Lens

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
Sign in / Sign up

Export Citation Format

Share Document