Liquid Crystals

by Khoo, Iam-Choon; Saleh, Bahaa E. A.

• ISBN13: 9780471751533
• ISBN10: 0471751537
• Edition: 2nd
• Format: Hardcover
• Copyright: 2007-03-09
• Publisher: Wiley-Interscience

Summary

The fundamental science and latest applications of liquid crystal technologies An excellent professional reference and superior upper-level student text, Liquid Crystals, Second Edition is a comprehensive treatment of all the basic principles underlying the unique physical and optical properties of liquid crystals. Written by an internationally known pioneer in the nonlinear optics of liquid crystals, the book also provides a unique, in-depth discussion of the mechanisms and theoretical principles behind all major nonlinear optical phenomena occurring in liquid crystals. Fully revised and updated with the latest developments, this Second Edition covers: Basic physics and optical properties of liquid crystals Nematics, as well as other mesophases such as smectics, ferroelectrics, and cholesterics Fundamentals of liquid crystals for electro-optics, and display and non-display related applications Various theoretical and computational techniques used in describing optical propagation through liquid crystals and anisotropic materials Nonlinear optics of liquid crystals, including updated literature reviews and fundamental discussions Structured to follow a natural sequence of instruction, from basic physics to the latest specialized optical, electro-optical, and nonlinear applications, Liquid Crystals is a textbook that grounds students in the fundamentals before introducing them to the most current discoveries in the field. Written in a clear, reader-friendly style, it features numerous figures, tables, and illustrations, including important and hard-to-find device and material parameters. Invaluable to students, researchers, and those working with liquid crystal applications in various industries, Liquid Crystals, Second Edition is the most comprehensive and up-to-date resource available.

Author Biography

Iam-Choon Khoo, PhD, is Distinguished Professor of Electrical Engineering at The Pennsylvania State University. Professor Khoo is internationally known for his pioneering and leading work in liquid crystals, and in nonlinear optical phenomena and applications. He is a Fellow of the Optical Society of America, IEEE, and the UK Institute of Physics.

Table of Contents

Preface	p. xiii
Introduction to Liquid Crystals	p. 1
Molecular Structures and Chemical Compositions	p. 1
Chemical Structures	p. 1
Electronic Properties	p. 3
Electronic Transitions and Ultraviolet Absorption	p. 3
Visible and Infrared Absolution	p. 4
Lyotropic, Polymeric, and Thermotropic Liquid Crystals	p. 6
Lyotropic Liquid Crystals	p. 6
Polymeric Liquid Crystals	p. 6
Thermotropic Liquid Crystals: Nematics, Cholesterics, and Smectics	p. 7
Other Liquid Crystalline Phases and Molecular Engineered Structures	p. 10
Mixtures and Composites	p. 11
Mixtures	p. 12
Dye-Doped Liquid Crystals	p. 13
Polymer-Dispersed Liquid Crystals	p. 14
Liquid Crystal Cells and Sample Preparation	p. 14
Bulk Thin Film	p. 15
Liquid Crystal Optical Slab Waveguide, Fiber, and Nanostructured Photonic Crystals	p. 17
References	p. 19
Order Parameter, Phase Transition, and Free Energies	p. 22
Basic Concepts	p. 22
Introduction	p. 22
Scalar and Tensor Order Parameters	p. 23
Long- and Short-Range Order	p. 25
Molecular Interactions and Phase Transitions	p. 26
Molecular Theories and Results for the Liquid Crystalline Phase	p. 26
Maier-Saupe Theory: Order Parameter Near T[subscript c]	p. 27
Nonequilibrium and Dynamical Dependence of the Order Parameter	p. 29
Isotropic Phase of Liquid Crystals	p. 32
Free Energy and Phase Transition	p. 32
Free Energy in the Presence of an Applied Field	p. 33
References	p. 35
Nematic Liquid Crystals	p. 36
Introduction	p. 36
Elastic Continuum Theory	p. 36
The Vector Field: Direct Axis n (r)	p. 36
Elastic Constants, Free Energies, and Molecular Fields	p. 38
Dielectric Constants and Refractive Indices	p. 41
dc and Low-Frequency Dielectric Permittivity, Conductivities, and Magnetic Susceptibility	p. 41
Free Energy and Torques by Electric and Magnetic Fields	p. 44
Optical Dielectric Constants and Refractive Indices	p. 45
Linear Susceptibility and Local Field Effect	p. 45
Equilibrium Temperature and Order Parameter Dependences of Refractive Indices	p. 47
Flows and Hydrodynamics	p. 51
Hydrodynamics of Ordinary Isotropic Fluids	p. 52
General Stress Tensor for Nematic Liquid Crystals	p. 55
Flows with Fixed Director Axis Orientation	p. 55
Flows with Director Axis Reorientation	p. 57
Field-Induced Director Axis Reorientation Effects	p. 58
Field-Induced Reorientation without Flow Coupling: Freedericksz Transition	p. 58
Reorientation with Flow Coupling	p. 61
References	p. 62
Cholesteric, Smectic, and Ferroelectric Liquid Crystals	p. 64
Cholesteric Liquid Crystals	p. 64
Free Energies	p. 64
Field-Induced Effects and Dynamics	p. 66
Twist and Conic Mode Relaxation Times	p. 69
Light Scattering in Cholesterics	p. 70
General Optical Propagation and Reflection: Normal Incidence	p. 70
Cholesteric Liquid Crystal as a One-Dimensional Photonic Crystal	p. 74
Cholesteric Liquid Crystals with Magneto-Optic Activity: Negative Refraction Effect	p. 78
Smectic and Ferroelectric Liquid Crystals: A Quick Survey	p. 80
Smectic-A Liquid Crystals	p. 82
Free Energy	p. 82
Light Scattering in SmA Liquid Crystals	p. 84
Smectic-C Liquid Crystals	p. 86
Free Energy	p. 86
Field-Induced Director Axis Rotation in SmC Liquid Crystals	p. 87
Smectic-C* and Ferroelectric Liquid Crystals	p. 88
Free Energy of Ferroelectric Liquid Crystals	p. 89
Smectic-C*-Smectic-A Phase Transition	p. 93
References	p. 95
Light Scatterings	p. 97
Introduction	p. 97
General Electromagnetic Formalism of Light Scattering in Liquid Crystals	p. 98
Scattering from Director Axis Fluctuations in Nematic Liquid Crystals	p. 100
Light Scattering in the Isotropic Phase of Liquid Crystals	p. 104
Temperature, Wavelength, and Cell Geometry Effects on Scattering	p. 107
Spectrum of Light and Orientation Fluctuation Dynamics	p. 109
Raman Scatterings	p. 111
Introduction	p. 111
Quantum Theory of Raman Scattering: Scattering Cross Section	p. 112
Brillouin and Rayleigh Scatterings	p. 115
Brillouin Scattering	p. 117
Rayleigh Scattering	p. 119
Nonlinear Light Scattering: Supraoptical Nonlinearity of Liquid Crystals	p. 120
References	p. 122
Liquid Crystal Optics and Electro-Optics	p. 124
Introduction	p. 124
Review of Electro-Optics of Anisotropic and Birefringent Crystals	p. 125
Anisotropic, Uniaxial, and Biaxial Optical Crystals	p. 125
Index Ellipsoid in the Presence of an Electric Field: Linear Electro-Optics Effect	p. 127
Polarizers and Retardation Plate	p. 128
Basic Electro-Optics Modulation	p. 130
Electro-Optics of Nematic Liquid Crystals	p. 131
Director Axis Reorientation in Homeotropic and Planar Cells: Dual-Frequency Liquid Crystals	p. 131
Freedericksz Transition Revisited	p. 133
Field-Induced Refractive Index Change and Phase Shift	p. 136
Nematic Liquid Crystal Switches and Displays	p. 138
Liquid Crystal Switch: On-Axis Consideration for Twist, Planar, and Homeotropic Aligned Cells	p. 139
Off-Axis Transmission, Viewing Angle, and Birefringence Compensation	p. 139
Liquid Crystal Display Electronics	p. 141
Electro-Optical Effects in Other Phases of Liquid Crystals	p. 142
Surface Stabilized FLC	p. 142
Soft-Mode FLCs	p. 144
Nondisplay Applications of Liquid Crystals	p. 146
Liquid Crystal Spatial Light Modulator	p. 146
Tunable Photonic Crystals with Liquid Crystal Infiltrated Nanostructures	p. 148
Tunable Frequency Selective Planar Structures	p. 148
Liquid Crystals for Molecular Sensing and Detection	p. 150
Beam Steering, Routing, and Optical Switching and Laser Hardened Optics	p. 152
References	p. 153
Electromagnetic Formalisms for Optical Propagation	p. 157
Introduction	p. 157
Electromagnetism of Anisotropic Media Revisited	p. 158
Maxwell Equations and Wave Equations	p. 158
Complex Refractive Index	p. 159
Negative Index Material	p. 160
Normal Modes, Power Flow, and Propagation Vectors in a Lossless Isotropic Medium	p. 163
Normal Modes and Propagation Vectors in a Lossless Anisotropic Medium	p. 164
General Formalisms for Polarized Light Propagation Through Liquid Crystal Devices	p. 168
Plane-Polarized Wave and Jones Vectors	p. 169
Jones Matrix Method for Propagation Through a Nematic Liquid Crystal Cell	p. 173
Oblique Incidence: 4X4 Matrix Methods	p. 175
Extended Jones Matrix Method	p. 177
Finite-Difference Time-Domain Technique	p. 181
The Implementation of FDTD Methods	p. 181
Example: FDTD Computations of the Twisted Nematic Cell in One Dimension	p. 186
References	p. 188
Laser-Induced Orientational Optical Nonlinearities in Liquid Crystals	p. 190
General Overview of Liquid Crystal Nonlinearities	p. 190
Laser-Induced Molecular Reorientations in the Isotropic Phase	p. 193
Individual Molecular Reorientations in Anisotropic Liquids	p. 193
Correlated Molecular Reorientation Dynamics	p. 196
Influence of Molecular Structure on Isotropic Phase Reorientational Nonlinearities	p. 198
Molecular Reorientations in the Nematic Phase	p. 200
Simplified Treatment of Optical Field-Induced Director Axis Reorientation	p. 201
More Exact Treatment of Optical Field-Induced Director Axis Reorientation	p. 204
Nonlocal Effect and Transverse Dependence	p. 205
Nematic Phase Reorientation Dynamics	p. 206
Plane Wave Optical Field	p. 206
Sinusoidal Optical Intensity	p. 210
Laser-Induced Dopant-Assisted Molecular Reorientation and Trans-Cis Isomerism	p. 211
DC Field Aided Optically Induced Nonlinear Optical Effects in Liquid Crystals: Photorefractivity	p. 213
Orientational Photorefractivity: Bulk Effects	p. 215
Some Experimental Results and Surface Charge/Field Contribution	p. 220
Reorientation and Nonelectronic Nonlinear Optical Effects in Smectic and Cholesteric Phases	p. 221
Smectic Phase	p. 221
Cholesteric Phase	p. 222
References	p. 223
Thermal, Density, and Other Nonelectronic Nonlinear Mechanisms	p. 227
Introduction	p. 227
Density and Temperature Changes Induced by Sinusoidal Optical Intensity	p. 230
Refractive Index Changes: Temperature and Density Effects	p. 233
Thermal and Density Optical Nonlinearities of Nematic Liquid Crystals in the Visible-Infrared Spectrum	p. 238
Steady-State Thermal Nonlinearity of Nematic Liquid Crystals	p. 240
Short Laser Pulse Induced Thermal Index Change in Nematics and Near-T[subscript c] Effect	p. 241
Thermal and Density Optical Nonlinearities of Isotropic Liquid Crystals	p. 243
Coupled Nonlinear Optical Effects in Nematic Liquid Crystals	p. 245
Thermal-Orientational Coupling in Nematic Liquid Crystals	p. 246
Flow-Orientational Effect	p. 247
References	p. 251
Electronic Optical Nonlinearities	p. 253
Introduction	p. 253
Density Matrix Formalism for Optically Induced Molecular Electronic Polarizabilities	p. 253
Induced Polarizations	p. 256
Multiphoton Absoiptions	p. 256
Electronic Susceptibilities of Liquid Crystals	p. 259
Linear Optical Polarizabilities of a Molecule with No Permanent Dipole	p. 259
Second-Order Electronic Polarizabilities	p. 262
Third-Order Electronic Polarizabilities	p. 264
Electronic Nonlinear Polarizations of Liquid Crystals	p. 266
Local Field Effects and Symmetry	p. 267
Symmetry Considerations	p. 268
Permanent Dipole and Molecular Ordering	p. 268
Quadrupole Contribution and Field-Induced Symmetry Breaking	p. 269
Molecular Structural Dependence of Nonlinear Susceptibilities	p. 269
References	p. 271
Introduction to Nonlinear Optics	p. 273
Nonlinear Susceptibility and Intensity-Dependent Refractive Index	p. 273
Nonlinear Polarization and Refractive Index	p. 273
Nonlinear Coefficient and Units	p. 276
General Nonlinear Polarization and Susceptibility	p. 277
Convention and Symmetry	p. 278
Coupled Maxwell Wave Equations	p. 282
Nonlinear Optical Phenomena	p. 284
Stationary Degenerate Four-Wave Mixing	p. 284
Optical Phase Conjugation	p. 288
Nearly Degenerate and Transient Wave Mixing	p. 291
Nondegenerate Optical Wave Mixing: Harmonic Generations	p. 294
Self-Focusing and Self-Phase Modulation	p. 297
Stimulated Scatterings	p. 303
Stimulated Raman Scatterings	p. 303
Stimulated Brillouin Scatterings	p. 306
Stimulated Orientational Scattering in Liquid Crystals	p. 311
Stimulated Thermal Scattering (STS)	p. 316
References	p. 317
Nonlinear Optical Phenomena Observed in Liquid Crystals	p. 319
Self-Focusing, Self-Phase Modulation, and Self-Guiding	p. 319
Self-Focusing and Self-Phase Modulation and Optical Limiting with Nematic Liquid Crystals	p. 319
Self-Guiding, Spatial Soliton, and Pattern Formation	p. 324
Optical Wave Mixing	p. 326
Stimulated Orientational Scattering and Polarization Self-Switching: Steady State	p. 326
Stimulated Orientational Scattering: Nonlinear Dynamics	p. 329
Optical Phase Conjugation with Orientation and Thermal Gratings	p. 332
Self-Starting Optical Phase Conjugation	p. 333
Liquid Crystals for All-Optical Image Processing	p. 337
Liquid Crystals as All-Optical Information Processing Materials	p. 337
All-Optical Image Processing	p. 339
Intelligent Optical Processing	p. 341
Harmonic Generations and Sum-Frequency Spectroscopy	p. 343
Optical Switching	p. 344
Nonlinear Absorption and Optical Limiting of Short Laser Pulses in Isotropic Phase Liquid Crystals and Liquids	p. 348
Introduction	p. 348
Nonlinear Fiber Array	p. 350
RSA Materials (C60 Doped ILC)	p. 351
Optical Limiting by TPA Materials (L34 Fiber Core Liquid)	p. 355
Conclusion	p. 358
References	p. 358
Index	p. 365
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