Optical bistability, regenerative oscillation, and monostable pulse generation in a liquid crystal bistable optical device.
A hybrid bistable optical device is realized by using a simple liquid crystal light modulator based on the dynamic scattering. Its low driving voltage and high transmission for the ON state make the amplification of feedback signal unnecessary and may facilitate a 2-D spatial array of devices. Regenerative oscillation and monostable pulse generation have also been demonstrated to study its transient behavior.
II Nonlinear Optics of Liquid Crystals
Publisher Summary This chapter discusses the nonlinear optics of the liquid crystals. The mechanisms for optically induced refractive index change in the nematic phase of liquid crystals, and related nonlinear optical processes such as optical wave mixings, self-focusing, and bistabilities are discussed. Liquid crystals are composed of large organic molecules with a typical chemical structure. As a result of intermolecular forces, the molecules tend to align themselves in some fixed direction. Most liquid crystal molecules are uniaxial, centrosymmetrical and nonpolar, although there is a class of liquid crystals that is ferroelectric and possesses large permanent dipole moments. The chapter focuses on selected nonlinear processes in which the extraordinarily large nonlinearity of liquid crystals has shed new light on the fundamental understanding of them, on processes that are on the threshold of being applicable to practical devices, and on special processes that can be obtained only with highly nonlinear materials.
Resonant Auger decay study of C1s -> pi* core-excited OCS
The present work aims at characterizing short-lived C1s((-1)) pi*((1)) core-excited states of the OCS molecule based on the analysis of the vibrational fine structure and lineshape profiles of the high-resolution resonant Auger decay spectra recorded at the excitation energies along the C1s -> pi* resonance in the binding energy region 15-19eV. Very different behavior in terms of lineshape and resonant enhancement is observed for the (A) over tilde, (B) over tilde and (C) over tilde final states. This is explained by (1) the variation in the C-O bond lengths for the states involved in the electronic relaxation and (2) different contributions in terms of Mulliken population to the molecular orbitals determining the electronic character of the corresponding states. Since the final-state geometries are known from a number of previous experiments and ab initio calculations, the geometry of the C1s((-1)) pi*((1)) intermediate states can be predicted in analogy with e.g. the N-2, CO2 and N2O molecules. (C) 2009 Elsevier B.V. All rights reserved. (Less)