Lee K.M.,Air Force Research Lab |
Lee K.M.,Azimuth Corporation |
Tabiryan N.V.,BEAM Engineering for Advanced Measurements |
Bunning T.J.,Air Force Research Lab |
White T.J.,Air Force Research Lab
Journal of Materials Chemistry | Year: 2012
Azobenzene-functionalized polymeric materials have proven capable of shape adaptive responses when irradiated with light. This work focuses on isolating the fundamental differences between the photogenerated mechanical output of glassy, polydomain azobenzene liquid crystal polymer networks (azo-LCN) upon exposure to either UV and blue-green irradiation. Profound differences in the fundamental photochemical mechanism are identified through spectroscopic examination of representative materials before and after irradiation with UV or blue-green light. The photomechanical response is further elucidated in structure-property examination to ascertain the role of crosslink density, azobenzene concentration, and azobenzene connectivity (crosslinked or pendant) on the photomechanical output. © 2012 The Royal Society of Chemistry. Source
Piccardi A.,Nonlinear Optics and OptoElectronics Laboratory NooEL |
Alberucci A.,Nonlinear Optics and OptoElectronics Laboratory NooEL |
Tabiryan N.,BEAM Engineering for Advanced Measurements |
Assanto G.,Nonlinear Optics and OptoElectronics Laboratory NooEL
Optics Letters | Year: 2011
We experimentally demonstrate and model dark spatial solitons in azo-doped liquid crystals, in the presence of saturation and nonlocality of the effective nonlinearity due to changes in molecular order. The guiding properties of dark solitons are probed with a weak input of different wavelength. © 2011 Optical Society of America. Source
BEAM Engineering for Advanced Measurements | Date: 2010-01-29
The objective of the present invention is providing optical systems for controlling with propagation of light beams in lateral and angular space, and through optical apertures. Said light beams include laser beams as well as beams with wide spectrum of wavelengths and large divergence angles. Said optical systems are based on combination of diffractive waveplates with diffractive properties that can be controlled with the aid of external stimuli such as electrical fields, temperature, optical beams and mechanical means.
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 99.99K | Year: 2011
Diffractive waveplates are optical components made of thin films of anisotropic materials by modulating their optical axis orientation in the plane of the waveplate. The family of diffractive waveplates wherein this modulation is axially symmetricÂ? vector vortex waveplates (VVWs) Â? impart a spiral phase modulation at a light beam propagated through the waveplate. As a result, the intensity of radiation is sharply decreased at the axis of the beam by many orders of magnitude, depending on the topological charge and quality of the VVW. Such transparent phase components can be successfully employed in coronagraphy allowing imaging of exoplanets at diffraction angle limit of their separation from the bright host star using small aperture telescopes, and they will allow increasing the imaging capability of large telescopes. To achievethis potential, VVWs shall possess with negligibly small singularity size (~ 2 micrometer) and be spectrally broadband in a large aperture (~ 25 mm). We propose to prove the feasibility of developing such components based on azobenzene photoalignment materials, liquid crystal polymers, and the optical printing technology that employs linear-to-axial polarization conversion. This feasibility will be proven in the Phase 1 by demonstrating achromatic VVWs in 700-900 nm spectral range and<10 micrometer singulary size.
BEAM Engineering for Advanced Measurements | Date: 2010-04-21
The objective of the present invention is providing a method for fabricating high quality diffractive waveplates and their arrays that exhibit high diffraction efficiency over large area, the method being capable of inexpensive large volume production. The method uses a polarization converter for converting the polarization of generally non-monochromatic and partially coherent input light beam into a pattern of periodic spatial modulation at the output of said polarization converter. A substrate carrying a photoalignment layer is exposed to said polarization modulation pattern and is coated subsequently with a liquid crystalline material. The high quality diffractive waveplates of the present invention are obtained when the exposure time of said photoalignment layer exceeds by generally an order of magnitude the time period that would be sufficient for producing homogeneous orientation of liquid crystalline materials brought in contact with said photoalignment layer. Compared to holographic techniques, the method is robust with respect to mechanical noises, ambient conditions, and allows inexpensive production via printing while also allowing to double the spatial frequency of optical axis modulation of diffractive waveplates.