Showing papers on "Organic photorefractive materials published in 2016"

Electronic, magnetic, and optical materials

Abstract: Introduction Classification of Materials Crystalline Materials Ceramics, Metals and Alloys, and Polymers Functional Classifi cation of Materials Crystal Structures Directions and Planes in Crystal Structures Interstitial Sites or Holes in Crystal Structures Coordination Numbers Radius Ratio Concept Crystal Structures of Different Materials Defects in Materials Point Defects in Ceramic Materials Kroger-Vink Notation for Point Defects Dislocations Stacking Faults and Grain Boundaries Microstructure-Property Relationships Amorphous Materials Nanostructured Materials Defects in Materials: Good News or Bad News? Electrical Conduction in Metals and Alloys Ohm's Law Sheet Resistance (Rs) Classical Theory of Electrical Conduction Drift, Mobility, and Conductivity Electronic and Ionic Conductors Limitations of the Classical Theory of Conductivity Resistivity of Metallic Materials Joule Heating or I2R Losses Dependence of Resistivity on Thickness Chemical Composition-Microstructure-Conductivity Relationships in Metals Resistivity of Metallic Alloys The Quantum Mechanical Approach to Conductivity Electrons in an Atom Electrons in a Solid Band Structure of Solids Concept of the Fermi Energy Level Fundamentals of Semiconductor Materials Intrinsic Semiconductors Temperature Dependence of Carrier Concentrations Band Structure of Semiconductors Direct- and Indirect-Bandgap Semiconductors Applications of Direct-Bandgap Materials Motions of Electrons and Holes Extrinsic Semiconductors Donor-Doped (n-Type) Semiconductors Acceptor-Doped (p-Type) Semiconductors Amphoteric Dopants, Compensation, and Isoelectronic Dopants Dopant Ionization Conductivity of Intrinsic and Extrinsic Semiconductors Effect of Temperature on the Mobility of Carriers The Effect of Dopant Concentration on Mobility Temperature Dependence of Conductivity Effect of Partial Dopant Ionization Effect of Temperature on the Bandgap The Effect of Dopant Concentration on the Bandgap (Eg) The Effect of Crystallite Size on the Bandgap Quantum Dots Semiconductivity in Ceramic Materials Fermi Energy Levels in Semiconductors Fermi Energy Levels in Metals Fermi Energy Levels in Semiconductors Electron and Hole Concentrations Fermi Energy Levels in Intrinsic Semiconductors Carrier Concentrations in Intrinsic Semiconductors Fermi Energy Levels in n-Type and p-Type Semiconductors Fermi Energy as a Function of the Temperature Fermi Energy Positions and the Fermi-Dirac Distribution Degenerate or Heavily-Doped Semiconductors Fermi Energy Levels across Materials and Interfaces Semiconductor p-n Junctions Formation of a p-n Junction Drift and Diffusion of Carriers Constructing the Band Diagram for a p-n Junction Calculation of Contact Potential Space Charge at the p-n Junction Electric Field Variation across the Depletion Region Variation of Electric Potential Width of the Depletion Region and Penetration Depths Reverse-Biased p-n Junction Diffusion Currents in a Forward-Biased p-n Junction Drift Currents in a p-n Junction Diode Based on a p-n Junction Reverse-Bias Breakdown Zener Diodes Semiconductor Devices Metal-Semiconductor Contacts Schottky Contacts Ohmic Contacts Solar Cells Light-Emitting Diodes Bipolar Junction Transistor Field-Effect Transistors Types of Field-Effect Transistors MESFET I-V Characteristics Metal Insulator Field-Effect Transistors Metal Oxide Semiconductor Field-Effect Transistors Linear Dielectric Materials Dielectric Materials Capacitance and Dielectric Constant Dielectric Polarization Local Electric Field (Elocal) Polarization Mechanisms-Overview Electronic or Optical Polarization Ionic, Atomic, or Vibrational Polarization Shannon's Polarizability Approach for Predicting Dielectric Constants Dipolar or Orientational Polarization Interfacial, Space Charge, or Maxwell-Wagner Polarization Spontaneous or Ferroelectric Polarization Dependence of the Dielectric Constant on Frequency Complex Dielectric Constant and Dielectric Losses Equivalent Circuit of a Real Dielectric Impedance (Z) and Admittance (Y) Power Loss in a Real Dielectric Material Equivalent Series Resistance and Equivalent Series Capacitance Ferroelectrics, Piezoelectrics, and Pyroelectrics Ferroelectric Materials Relationship of Ferroelectrics and Piezoelectrics to Crystal Symmetry Electrostriction Ferroelectric Hysteresis Loop Piezoelectricity Direct and Converse Piezoelectric Effects Piezoelectric Behavior of Ferroelectrics Piezoelectric Coefficients Tensor Nature of Piezoelectric Coefficients Relationship between Piezoelectric Coefficients Applications of Piezoelectrics Devices Based on Piezoelectrics Technologically Important Piezoelectrics Lead Zirconium Titanate Applications and Properties of Hard and Soft Lead Zirconium Titanate Ceramics Electromechanical Coupling Coefficient Illustration of an Application: Piezoelectric Igniter Recent Developments Piezoelectric Composites Pyroelectric Materials and Devices Magnetic Materials Origin of Magnetism Magnetization (M), Flux Density (B), Magnetic Susceptibility (chim), Permeability (mu), and Relative Magnetic Permeability (mur) Classification of Magnetic Materials Ferromagnetic and Ferrimagnetic Materials Other Properties of Magnetic Materials Magnetostriction Soft and Hard Magnetic Materials Hard Magnetic Materials Isotropic, Textured (Oriented), and Bonded Magnets Soft Magnetic Materials Magnetic Data-Storage Materials Index

Impact of the photorefractive and pyroelectric-electro-optic effect in lithium niobate on whispering-gallery modes.

Abstract: Whispering-gallery resonators made of undoped and MgO-doped congruently grown lithium niobate are used to study electro-optic refractive index changes. Hereby, we focus on the volume photovoltaic and the pyroelectric effect, both providing an electric field driving the electro-optic effect. Our findings indicate that the light-induced photorefractive effect, combining the photovoltaic and electro-optic effect, is present only in the non-MgO-doped lithium niobate for exposure with light having wavelengths of up to 850 nm. This leads to strong resonance frequency shifts of the whispering-gallery modes. No photorefractive effect was observed in the MgO-doped material. One has to be aware that surface charges induced by the pyroelectric effect result in a similar phenomenon and are present in both materials.

Photorefractive Response: An Approach from the Photoconductive Properties

Abstract: Photorefractive phenomenon is based on the refractive index modulation due to the redistribution of charge carriers generated upon the illumination of the interference of laser beams in the materials possessing both photoconductivity and optical nonlinearity. Photogeneration of charge carriers in the bright regions of the interferencing beams initiates the photorefractive phenomenon. Thus the photogeneration of charge carrier upon photoexcitation is first step for the photorefractive phenomenon. Through several photophysical processes, positive and negative charge carriers are periodically distributed to form the refractive index modulation via the first-order electro-optics effect of the Pockels effect. In this chapter, the role and the influence of photoconductive properties in organic photorefractive materials on the photorefractive performance are discussed, and the strategy for obtaining the better and the best photorefractive performance, higher diffraction efficiency, and faster speed of the grating formation of the corresponding materials is discussed from the point of view of the photoconductivity.

Photorefractive Smectic Mesophases

Abstract: The orientational contribution pointed out the major contribution of the molecular first order susceptibility to the index modulation in organic photorefractive materials. This discovery leads the way to the use of liquid crystals as PR materials due to their spontaneous birefringence and to the many possible electric field-induced reorientational effects. In this chapter, we are focusing on the structure and electro-optic properties of the smectic phases. After a brief introduction to the different phases (A and C), we will discuss the specific properties each phase contribute to in a photorefractive liquid crystal system. The theory of the molecular alignment into the photo-generated space-charge field is detailed incorporating the particularities due to liquid crystal phases and light polarization. Some specific cases are analyzed in detail such as the application of an AC field and the use of bistable devices which bring both long-term stability and nondestructive readout.