Multi-level optical switch of diffractive light from a BCT photonic crystal based on an azo component-doped HPDLC
0
Citation
0
Reference
20
Related Paper
Keywords:
Component (thermodynamics)
Cite
We investigated optically controllable gray-level diffraction from a body-centered tetragonal photonic crystal that was based on an azo-dye-doped holographic polymer dispersed liquid crystal. The sample is fabricated by use of two-beam interference with multi-exposure. Bichromatic pumping beams at various intensities were used to pump the sample to change the concentration of the cis isomer and, in turn, modulate the effective index of the photonic crystals as well as their diffraction intensity. Three pumping processes were utilized to produce gray-level switching of diffractive light. This study demonstrates the optimum gray-level to be 15-level of up-step and down-step. The simulation of the diffraction intensity under bichromatic pumping sources was also studied.
Tetragonal crystal system
Diffraction efficiency
Cite
Citations (0)
Fabrication of an all-optical switchable holographic liquid crystal (LC) Fresnel lens based on azo-dye-doped polymer-dispersed LCs is reported using a Michelson interferometer. It is found that, upon circularly polarized photoirradiation, the diffraction efficiency of the fabricated Fresnel lens was increased significantly in a reversible manner. We believe this is due to the anisotropy induced by reorientation of the LC molecules coupled with azo-dye molecule orientation due to trans-cis-trans photoisomerization, which modulates the refractive index of the LC-rich regions. We also studied the effect of azo dye on the polarization dependency of the fabricated lens.
Fresnel lens
Diffraction efficiency
Cite
Citations (29)
We demonstrate a two-dimensional absorbing photonic crystal with a uniform real part of the refractive index, but a periodically modulated imaginary part.It was realized through back-filling the voids of a periodic array of azo-dye-doped polymeric disks with the same undoped polymers.The photonic crystals were characterized using the diffraction method.The experimental results showed that only the light in the spectral range where the azo-dye absorbed was diffracted, indicating that a purely absorbing photonic crystal was formed.This absorbing photonic crystal also showed switchable diffraction properties due to the trans-cis isomerization of the azo-dye under the light pump.
Refractive index contrast
Diffraction efficiency
Optical materials
Cite
Citations (11)
Holographic polymer dispersed liquid crystal (HPDLC) based distributed feedback (DFB) lasers were prepared with poly (-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene-vinylene) (MEH-PPV) film as the active medium layer. The HPDLC grating film was fabricated via holographic induced photopolymerization. The pure film spectra of MEH-PPV and the amplified spontaneous emission (ASE) spectrum were investigated. The laser device was single-longitudinal mode operation. The tunability of the HPDLC DFB laser was achieved by selecting different grating periods. The lasing performances were also characterized and compared from different diffraction orders. The lasing threshold increased with the diffraction order and the third order laser possessed the largest conversion efficiency in this device. The experimental results were in good agreement with the theoretical calculations.
Diffraction efficiency
Cite
Citations (17)
We report on theoretical and experimental investigations of optical wave propagations in two-dimensional photonic lattice structures formed in a holographic polymer-dispersed liquid crystal (HPDLC) film. In the theoretical analysis we employed the 2×2 matrix formulation and the statistical thermodynamics model to analyze the formation of anisotropic photonic lattice structures by holographic polymerization. The influence of multiple reflections inside an HPDLC film on the formed refractive index distribution was taken into account in the analysis. In the experiment we fabricated two-dimensional photonic lattice structures in an HPDLC film under three-beam interference holographic polymerization and performed optical measurements of spectral transmittances and wavelength dispersion. We also demonstrated the electrical control capability of the fabricated photonic lattice structure and its dependence on incident wave polarization. These measured results were compared with the calculated ones by means of photonic band and beam propagation calculations.
Cite
Citations (12)
We report on the fabrication and characterization of a surface-emitting distributed feedback (DFB) organic semiconductor laser based on a holographic polymer dispersed liquid crystal (HPDLC) transmission grating.
Cite
Citations (8)
Cite
Citations (7)
This study demonstrates all optical switches between the four diffractive light levels of a body-centered tetragonal photonic crystal. The sample is based on holographic polymer-dispersed liquid crystals that are fabricated using a twobeam interference with multiple exposures. The switching mechanism bases on the effective index modulation of the PC that contains a liquid crystal/azo-dye mixture could be controlled by two pumping laser beams. The switching time between the blue-laser-pumped and the blue-and-green-laser-pumped levels is fast.
Tetragonal crystal system
Optical Pumping
Cite
Citations (2)
Holographic polymer dispersed liquid crystal (HPDLC) memory is fabricated by a photoinduced phase separation comprised of polymer and liquid crystal (LC) phases using laser light interference exposures. The anisotropic diffraction induced by the alignment of LC in the periodic structure of the HPDLC memory is applied to reconstruct the configuration contexts for the optically reconfigurable gate arrays. Optical reconfiguration for various circuits under parallel programmability is implemented by switching the polarization state of incident light on the HPDLC memory using a spatial light modulator.
Diffraction efficiency
Control reconfiguration
Spatial light modulator
Cite
Citations (13)
We have developed an azo-dye-doped acrylate-based material formulation for holographic lithography. Volume phase gratings and two-dimensional photonic crystals were demonstrated by recording the interference patterns of two and three coherent beams in this material formulation. The dependence of the first-order Bragg diffraction efficiency of the gratings on the exposure intensity of the writing light was investigated. We have achieved a volume phase grating with a diffraction efficiency of 72%. These azo-dye-functionalized photonic structures showed an excellent all-optical switching behaviour, which was attributed to the imaginary refractive index changes caused by the trans–cisisomerization-induced absorption changes of the azo-dyes. Such photonic structures are potentially useful in the future development of all-optical devices.
Diffraction efficiency
Interference lithography
Volume hologram
Cite
Citations (23)