Holographically formed Bragg reflection gratings recorded in polymer-dispersed Liquid crystal cells using a He-Ne laser

Abstract

Bragg reflection gratings are holographically recorded in polymer-dispersed liquid crystal materials by using the 632.8-nm wavelength of the He-Ne laser. Mixtures of the commercially available E8 nematic liquid crystal, pentafunctional monomers, and photooxidant dye methylene blue are employed. We demonstrate that Bragg reflection gratings can be formed in this acrylate photopolymer system with reflection efficiencies of 52% with a peak notch at 1165 nm. We also present results for the switching characteristics of these gratings with switching fields on the order of 6MV∕m and rise times of 62μs.

Effects of Monomer Functionality on Switchable Holographic Gratings Formed in Polymer‐Dispersed Liquid‐Crystal Cells

“…Having synthesized HPDLC transmission gratings by using the 633 nm wavelength from an He-Ne laser, we recently presented preliminary results on the diffraction properties of thus-formed HPDLC gratings. [1,2] To our knowledge, the diffraction properties of HPDLC transmission gratings formed by using the HeNe laser have not been studied in any detail. We therefore conducted a series of experiments on such gratings in order to better understand their formation and diffraction characteristics.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] Holographic polymer-dispersed liquid crystals (HPDLCs) complement conventional polymer-dispersed liquid crystals (PDLCs) used for electro-optical applications. [14][15][16][17][18][19][20][21][22][23][24][25][26] Switchable diffractive optical devices can be fabricated by holographic techniques; a spatially periodic variation in the refractive index of the HPDLC composite material can be realized within the interference pattern of coherent laser beams.…”

A review of the electro-optical properties and their modification by radiation in polymer-dispersed liquid crystals and thin films containing CdSe/ZnS quantum dots

“…It may be possible to take advantage of the preferred properties of the polymer, liquid crystal, and semiconductor quantum dots and design a highly sensitive, cost-effective, and user-friendly radiation detector. It is precisely for this reason that we have been interested in the potential applications of these apparently two different classes of materials, PDLCs and CdSe/ZnS quantum dots for radiation detection [30][31][32]37,43,[51][52][53][54][55][56][57]. As the data presented in this review show the electro-optical properties of both the PDLCs and polymer films containing CdSe/ZnS quantum dots are sensitive to changes in the local electric fields brought about by the absorption of gammarays.…”

“…The PDLC-based periodic structures (HPDLCs), which can be fabricated by using holographic techniques, exhibit even more interesting electro-optical properties, and they too are the basis for many advanced optical devices, like switchable holographic gratings (SHGs) and photonic bandgap structures [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50]. Since these devices respond to electric fields (as we show in subsequent paragraphs), their performance is sensitive to external parameters that can affect the internal electric field within the device.…”

Light distribution modulated diffuse reflectance spectroscopy

“…LC o e n n n = + and LC φ and M φ were the fractions of LC and NOA65, respectively [11]. The source and detection areas both had diameter of 400 μm, NA = 0.22, and their center-to-center separation was 2 mm.…”