Diffraction Efficiency of Reflection Holograms in Cubic Photorefractive Piezoelectric Crystals of 43m Symmetry Class

2009 ◽  
Vol 5 (3) ◽  
pp. 286-289 ◽  
Author(s):  
V. V. Shepelevich ◽  
V. N. Naunyka
Keyword(s):  
Diffraction Efficiency ◽  
Symmetry Class ◽  
Piezoelectric Crystals

scholarly journals Diffraction Efficiency Characteristics for MEMS-Based Phase-Only Spatial Light Modulator with Nonlinear Phase Distribution

Photonics ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 62
Author(s):  
Remington S. Ketchum ◽  
Pierre-Alexandre Blanche
Keyword(s):  
Diffraction Efficiency ◽  
High Speed ◽  
Phase Distribution ◽  
Complex Structure ◽  
Spatial Light Modulators ◽  
Light Modulator ◽  
Micro Electro Mechanical Systems ◽  
Light Modulators ◽  
Nonlinear Phase ◽  
Liquid Crystal On Silicon

Micro-electro mechanical systems (MEMS)-based phase-only spatial light modulators (PLMs) have the potential to overcome the limited speed of liquid crystal on silicon (LCoS) spatial light modulators (SLMs) and operate at speeds faster than 10 kHz. This expands the practicality of PLMs to several applications, including communications, sensing, and high-speed displays. The complex structure and fabrication requirements for large, 2D MEMS arrays with vertical actuation have kept MEMS-based PLMs out of the market in favor of LCoS SLMs. Recently, Texas Instruments has adapted its existing DMD technology for fabricating MEMS-based PLMs. Here, we characterize the diffraction efficiency for one of these PLMs and examine the effect of a nonlinear distribution of addressable phase states across a range of wavelengths and illumination angles.

scholarly journals Holographic Recording Performance of Acrylate-Based Photopolymer under Different Preparation Conditions for Waveguide Display

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 936
Author(s):  
Zhongwen Shen ◽  
Yishi Weng ◽  
Yuning Zhang ◽  
Chuang Wang ◽  
Ao Liu ◽  
...  
Keyword(s):  
Augmented Reality ◽  
Diffraction Efficiency ◽  
Green Light ◽  
Holographic Recording ◽  
Holographic Gratings ◽  
Preparation Conditions

This work proposes a green light-sensitive acrylate-based photopolymer. The effects of the preparation conditions for the waveguide applied volume holographic gratings (VHGs) were experimentally investigated. The optimum preparation conditions for holographic recording were revealed. After optimization, the peak of VHG diffraction efficiency reached 99%, the diffractive wavelength bandwidth increased from 13 nm to 22 nm, and the corresponding RIM was 0.06. To prove the wide application prospect of the acrylate-based photopolymer in head-mounted augmented reality (AR) displays, green monochromatic volume holographic waveguides were fabricated. The display results showed that the prototype was able to achieve a 28° diagonal FOV and possessed a system luminance of 300 cd/m2.

Relaxation Polarization Dependence of Circular Vector Gratings in Azobenzene Glassy Molecular Films

2020 ◽  
Vol 850 ◽  
pp. 285-290
Author(s):  
Andris Ozols ◽  
Peteris Augustovs ◽  
Kaspars Traskovskis ◽  
Valdis Kokars ◽  
Lauma Laipniece ◽  
...  
Keyword(s):  
Diffraction Efficiency ◽  
Relaxation Times ◽  
Grating Period ◽  
Volume Density ◽  
Laser Beams ◽  
Relaxation Polarization ◽  
Polarized Beam ◽  
Sandwich Type ◽  
Phd Thesis ◽  
532 Nm

Holographic grating recording and relaxation is studied in different azobenzene molecular glassy films by circularly orthogonally polarized 532 nm laser beams L and R. The readout was made by circularly polarized (R or L) 632.8 nm laser beam. Sandwich-type samples (glass-film-glass) were also studied. Maximum diffraction efficiency of 81% has been achieved in sandwich-type AR-173 film. The following relaxation features have been found: after reaching diffraction efficiency (DE) maximum no DE decay took place; DE read out by R-polarized beam was always higher than that by L-polarized beam; in sandwich-type samples DE decayed until zero when read out by R-polarization whereas DE was zero when read out by L-polarization. 50% relaxation times varied from 4 to 44 minutes, and they mainly decreased when grating period was increased. The observed relaxation peculiarities can be understood if one assumes that volume birefringence grating (VBG) is recorded followed by volume density grating (VDG) and surface relief grating (SRG) recording. R-polarization "feels" all gratings whereas L-polarization only VDG and SRG. At large exposures VDG and SRG dominate. These results confirm the conclusion made by J.Mikelsone in her 2018 PhD thesis that birefringence grating recording in azobenzene materials is a neccessary condition for SRG appearance.

Investigation on dynamic holographic display in liquid crystal film doped with carbon dots

2020 ◽  
Vol 10 (6) ◽  
pp. 780-787
Author(s):  
Hongyue Gao ◽  
Suna Li ◽  
Jicheng Liu ◽  
Wen Zhou ◽  
Fan Xu ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Electric Field ◽  
Real Time ◽  
Diffraction Efficiency ◽  
Carbon Dots ◽  
Applied Electric Field ◽  
Light Polarization ◽  
Forming Process ◽  
Time Dynamic ◽  
Holographic Display

In this paper, we studied the holographic properties of liquid crystal (LC) thin film doped with carbon dots (CDs) which can be used as real-time holographic display screen. The maximum value of diffraction efficiency can reach up to 30% by using a low applied electric field 0.2 V/μm. Holograms in the LC film can be dynamically formed and self-erased. The hologram build-up time and the hologram self-erasure time in the material is fast enough to realize video refresh rate. In addition, the forming process of hologram was studied. The holographic diffraction efficiency was measured depending on the intensity of recording light, applied electric field, the intensity of readout light, and readout light polarization direction. Triple enhancement of the diffraction efficiency value by the modulation of voltage under the condition of low recording energy is presented. Therefore, we develop an easy way to obtain real-time dynamic holographic red, green and blue displays with high diffraction efficiency, which allow the LC film doped with CDs to be used as a holographic 3D display screen.

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