Nelson V. Tabirian

Time-resolved studies of photoinduced birefringence in azobenzene dye-doped polymer films

We measured transient photoinduced birefringence (delta n) in various azobenzene dye films by pumping with a nanosecond pulse at 532 nm and probing at 633 nm. The switch-on times for the photoinduced birefringence range from nanoseconds to milliseconds and are systematically related with the lowest optical transition energies for those films. Moreover, our results suggest that the transient photoinduced birefringence measurement is a convenient way to determine the relative energies of pi-pi(*) and n-pi(*) states in azo-based materials.

Potential application of Periodically Aligned Liquid Crystal cell for projection displays

Transversely modulated nematic liquid crystal cell is suggested as an element of projection display. Equilibrium of the cell is studied and its optical performance is evaluated. High contrast ratio is predicted

Beam combining using orientational stimulated scattering in liquid crystals

The possibility of beam combining and cleanup using orientational stimulated scattering in a nematic liquid crystal is considered. We numerically study the dynamics of the process and find that backconversion process tends to limit the effective interaction strength. The instability of the steady state of cross-phase modulation is demonstrated, during which both waves have the same frequency. We show that high conversion efficiency can be achieved and that the shape and wavefront of the amplified output signal are robust with respect to the amplitude and phase distortions of the input pump. copy 2005 Optical Society of America

Beam clean-up and combining using orientational stimulated scattering in liquid crystals

Beam clean-up and combining using stimulated orientational scattering in nematics is considered. Dynamics of the process is studied, high conversion efficiency and stability with respect to pump fluctuations is demonstrated. Thus, we have demonstrated the possibility of beam clean-up by modeling the process of SOS in NLC. We showed that high conversion efficiency can be achieved, and that the shape and wave-front of the amplified output signal are robust with respect to amplitude and phase distortions of the input pump. We found that the process is limited in longitudinal direction due to the emerging power back-transfer from amplified signal into the pump wave. In summary, Stimulated Orientational Scattering in nematic liquid crystals promises very good prospects for beam clean-up and combining.

Implementation of 3D Angular Selective Achromatic Diffraction Optical Grating Device

Abstract : Angular Selective Achromatic Diffraction Optical Grating (ASADOG) device has been implemented. Surface reflective grating had 1200 lines per mm. Two identical volume holograms were implemented using Photo-Thermo- Refractive (PTR) glass technology, with spatial frequency 1697 lines per mm. Sequential diffraction of incident light by surface grating by first volume grating and then by second one oriented at 90 degrees resulted in angular selection of incident beam, completely achromatic within the spectral range from red to blue including.

Chromatic aberration corrected switchable optical systems

Chromatic aberrations of diffractive waveplate optics for imaging applications can be corrected for different switchable states. Different opportunities for lenses and prisms, and their limitations are discussed.

Manipulating Light and Images with 4G Optics: Digital Polarization Holography Using Liquid Crystals

Near 100% broadband efficiency of polarization holograms provides opportunities for shaping light beams, imaging, and displays. Thin, flexible and switchable between different optical states and functions, novel optical components and systems are smarter than ever.

Materials and Technology for Polarization Holography and Diffractive Waveplates

The principles of polarization holography and recent advances in materials and technology are reviewed. High efficiency and spectrally and angularly broadband diffraction inherent to polarization gratings challenges Bragg gratings for many applications opening new prospects.