Читать книгу Liquid Crystals - Iam-Choon Khoo - Страница 4

1 Chapter 1Figure 1.1. Molecular structure of a typical liquid crystal.Figure 1.2. Molecular structure of a heterocyclic liquid crystal.Figure 1.3. Molecular structure of an organometallic liquid crystal.Figure 1.4. Molecular structure of a sterol.Figure 1.5. Molecular structure of 5CB (pentyl cyanobiphenyl).Figure 1.6. The π → π^* electronic transitions in a benzene molecule.Figure 1.7. Transmission spectra of nematic liquid crystals: (a) 5CB; (b) N‐...Figure 1.8. Chemical structure and cartoon representation of sodium dodecyl ...Figure 1.9. Three different types of polymeric liquid crystals: (a) vinyl ty...Figure 1.10. Polymeric liquid crystals: (a) main chain; (b) side chain.Figure 1.11. Self‐organization of the rod‐shaped LC molecules via local and ...Figure 1.12. Arrangement of dipoles in the centrosymmetric bulk crystal such...Figure 1.13. Molecular arrangements of liquid crystals: (a) smectic‐A; (b) s...Figure 1.14. A shuttlecock‐shaped liquid crystal formed by incorporating ful...Figure 1.15. Molecular structures of the four constituents making up the liq...Figure 1.16. Phase diagram of the mixture of two liquid crystals.Figure 1.17. Alignment of a dichroic dye‐doped nematic liquid crystal: (a) b...Figure 1.18. Schematic depiction of a polymer‐dispersed liquid crystal mater...Figure 1.19. Nematic liquid crystal cells: (a) homeotropically aligned; (b) ...Figure 1.20. (a) CLC with focal conic structure as a result of director axis...Figure 1.21. Left: Image of logo obstructed by a thin CLC cell with focal co...Figure 1.22. Schematic depiction of the makeup of a blue-phase liquid crysta...Figure 1.23. Reflectance from BPLC in polycrystalline (lower photo) and sing...Figure 1.24. Tunable micro‐ and nano‐photonic structures incorporating liqui...Figure 1.25. Immobile LC layer around a plasmonic nanostructure (not drawn t...Figure 1.26. Schematic of a focused laser propagating through the guiding (l...Figure 1.27. A capillary filled with dye‐doped BPLC core for random laser ac...

2 Chapter 2Figure 2.1. Coordinate system defining the microscopic order parameter of a ...Figure 2.2. Schematic depiction of the numerical solution of the two transce...Figure 2.3. (a) Observed oscilloscope trace of the diffracted signal in a dy...Figure 2.4. Observed buildup times of the diffracted signal associated with ...Figure 2.5. Schematic depiction of the molecular levels involved in ground e...Figure 2.6. Free energies F(Q) for different temperatures T. At T = T_c, ∂

3 Chapter 3Figure 3.1. (a) Twist deformation in a nematic liquid crystal; (b) splay def...Figure 3.2. A homeotropic nematic liquid crystal with strong surface anchori...Figure 3.3. Soft‐boundary condition. The applied field will reorient both th...Figure 3.4. Dispersion data of the dielectric constant ε_|| and ε Figure 3.5. Dispersion data of the dielectric constant ε_|| and ε Figure 3.6. Measured birefringence De = ε_|| − ε_⊥ of three ...Figure 3.7. (a) Temperature dependence of the refractive indices of 5CB in t...Figure 3.8. Plot of dn_||/dT and dn_⊥/dT for the liquid crystal for te...Figure 3.9. An elementary volume of fluid moving at velocity v (r, t) in spa...Figure 3.10. Stresses acting on opposite planes of an elementary volume of f...Figure 3.11. Sheer flow in the presence of an applied magnetic field.Figure 3.12. Pure twist deformation induced by an external magnetic field H ...Figure 3.13. Director axis reorientation causing flows.

4 Chapter 4Figure 4.1. (a) Helical arrangement of the director axis in a cholesteric li...Figure 4.2. Field‐induced untwisting of a cholesteric liquid crystal: (a) id...Figure 4.3. Reflection and transmission of circularly polarized light in a c...Figure 4.4. (a) Relation between frequency (ω_r) and wave vector (l) ...Figure 4.5. Replot of Figure 4.1(a) by distinguishing the different polariza...Figure 4.6. Different branches of ω_r – k relation for a cholesteric ...Figure 4.7. The value of (b − a)/(b + a) for different branches.Figure 4.8. (a) Transmission of randomly polarized light (containing right‐ ...Figure 4.9. (a) Numerical calculated photonic band structure for axial propa...Figure 4.10. Photonic band structure for RCP eigenmode near band edge k_z ...Figure 4.11. Dispersion relationship near the band‐edge for cholesteric liqu...Figure 4.12. Schematic of polarization rotation of a linearly polarized ligh...Figure 4.13. (a) Plot of transmission T, polarization figure‐of‐merit (PF), ...Figure 4.14. Vector laser beams with (left) radial polarization and (right) ...Figure 4.15. Time evolution of the PBG shift associated with crystalline def...Figure 4.16. (a) A smectic‐A liquid crystal. (b) A liquid crystal that exhib...Figure 4.17. Splay distortion in a SmA liquid crystal.Figure 4.18. Measured values of bend and splay elastic constant in the nemat...Figure 4.19. Directions of the applied field components of H relative to the...Figure 4.20. Rotation of the C axis around the layer normal; no change in la...Figure 4.21. A helically modulated smectic‐C* liquid crystal, the directions...

5 Chapter 5Figure 5.1 Scattering of light from an elementary volume located at r.Figure 5.2. Coordinate system for analyzing light scattering in NLCs in term...Figure 5.3. Geometries for an intense scattering of the incident light. Note...Figure 5.4. Photograph of the transmitted laser beam through a NLC film (100...Figure 5.5. Experimentally measured scattering loss in a NLC (E46) that is h...Figure 5.6. Raman scattering involving the generation of Stokes and anti‐Sto...Figure 5.7. A typical spectrum of light spontaneously scattered from a liqui...Figure 5.8. Wave vector addition rule for the Brillouin scattering processes...Figure 5.9. Typical laser‐nematic director axis interaction geometry in a wa...

6 Chapter 6Figure 6.1. Schematic of a typical liquid crystal display pixel consisting o...Figure 6.2. Index ellipsoid for a plane‐polarized optical wave propagating a...Figure 6.3. Typical electro‐optic modulation scheme with polarizer–analyzer ...Figure 6.4. Various states of polarization resulting from the addition of tw...Figure 6.5. Capacitance measurements of an undoped 5CB and a CdSe‐doped 5CB ...Figure 6.6. Applied electric field‐director axis interaction geometry for (a...Figure 6.7. Director axis reorientation profile in the cell at various appli...Figure 6.8. Tilting and unwinding of the director axis of a 90° twisted NLC ...Figure 6.9. Light propagating through an initially homeotropic LC cell. The ...Figure 6.10. Schematic of a ferroelectric liquid crystal light switch with p...Figure 6.11. A SMFLC switching set‐up.Figure 6.12. Schematic of the various components of a typical OALCSLM operat...Figure 6.13. Non‐close‐packed inverse opal photonic crystal structure.Figure 6.14. Electrical tuning of Bragg reflection peak of NLC filled non‐cl...Figure 6.15. (a) Unit cell of an all‐dielectric polarization‐independent FSS...Figure 6.16. Transmission spectra of an all‐dielectric FSS with a liquid cry...Figure 6.17. Schematic depiction of aligned liquid crystal for chemical sens...

7 Chapter 7Figure 7.1. Paired metallic nanorods that exhibits negative index of refract...Figure 7.2. (a) A planar aligned nematic liquid crystal containing core‐shel...Figure 7.3. Illustration of a plane light wave propagating along z‐axis thro...Figure 7.4. Index ellipsoid for a uniaxial medium such as nematic liquid cry...Figure 7.5. Propagation of a polarized light through a birefringent phase pl...Figure 7.6. Schematic depiction of a pixel element that consists of an input...Figure 7.7. The N + 1 layers representation of an LC cell between polarizers...

8 Chapter 8Figure 8.1. Laser‐induced molecular alignment along the direction of the opt...Figure 8.2. Interaction of a linearly polarized light with an anisotropic (b...Figure 8.3. Observed dependence of the orientation relaxation time as a func...Figure 8.4. Measured optical nonlinear susceptibility as a function of the t...Figure 8.5. Schematic of the interaction geometry involving a linearly polar...Figure 8.6. Schematic depiction of the director axis reorientation profile i...Figure 8.7. (a) Plot of ω_θ/ω₀ as a function of ω₀/dFigure 8.8. Schematic diagram of the optical fields and their propagation di...Figure 8.9. Typical observed temperature dependence (dots) of the nonlinear ...Figure 8.10. (Top) Molecular structures of a commercial dye DR1, MR dye, and...Figure 8.11. Schematic depiction of the surface and bulk space‐charge field ...Figure 8.12. Schematic depiction of the optical wave mixing configuration to...Figure 8.13. (a) Typical dependence of the PR self‐diffraction efficiency on...Figure 8.14. Smectic‐C liquid crystal axis azimuthal rotation by an external...Figure 8.15. “Bookshelf‐like” configuration of a ferroelectric liquid crysta...

9 Chapter 9Figure 9.1. Absorption spectra of four liquid crystals.Figure 9.2. (a) Single‐photon absorption process; (b) two‐photon absorption ...Figure 9.3. (a) Molecules are pulled toward regions of higher field strength...Figure 9.4. Schematic depiction of the radial components of the Maxwell stre...Figure 9.5. Experimental setup for probing the dynamics of laser‐induced tra...Figure 9.6. Interference of the propagative index gratings (arising from ele...Figure 9.7. Oscilloscope trace of the observed probe diffraction evolution w...Figure 9.8. Oscilloscope traces of the thermal grating decay dynamics (time ...Figure 9.9. Observed dependence of the period of oscillations (see Figure 9....Figure 9.10. Temperature dependence of the refractive indices of E7 at 10.6 ...Figure 9.11. Experimentally measured steady‐state refractive index dependenc...Figure 9.12. Observed He–Ne probe diffraction from the isotropic liquid crys...Figure 9.13. Interaction of an extraordinary wave laser with a homeotropical...Figure 9.14. Polarization grating is generated by interfering two coherent c...Figure 9.15. Geometry of interaction for pulsed laser‐induced flow‐orientati...Figure 9.16. Oscilloscope trace of the probe diffraction showing the observe...Figure 9.17. Oscilloscope trace of probe beam diffraction from cross‐polariz...Figure 9.18. Observed nonlinear index coefficients and response times of maj...Figure 9.19. Some observed nonlinear index coefficients and response times o...Figure 9.20. Schematic depiction of the experimental setup for phase‐matched...Figure 9.21. Diffraction efficiency as a function of the grating spacing for...Figure 9.22. Dynamical dependence of the probe diffractions when the referen...Figure 9.23. (a) Schematic depiction of the experimental setup for optical p...

10 Chapter 10Figure 10.1. Schematic depiction of the energy level structure of a multilev...Figure 10.2. Interaction of the electric field E with the dipole moment d of...Figure 10.3. (a) Schematic depiction of the time evolution of the electronic...Figure 10.4. (a) Single‐photon transition. (b) Two‐photon absorption transit...Figure 10.5. A typical liquid crystal molecule molecular energy levels showi...Figure 10.6. (Upper) The real part of the complex refractive index, n_o(ω...Figure 10.7. (Upper) The real part of the complex refractive index, n_o(ω...Figure 10.8. Molecular structure of MBBA showing the presence of two benzene...Figure 10.9. Measured n₂ values of three organic liquids with femtoseconds ...Figure 10.10. Measured effective two‐photon absorption coefficient of the or...

11 Chapter 11Figure 11.1. (a) Three‐wave mixing process involving the mixing of two frequ...Figure 11.2. Temporal and spatial frequency wave mixings in a nonlinear opti...Figure 11.3. Forward wave mixing process involving side‐diffracted beams.Figure 11.4. Wave vector addition diagram for the process k₃ = 2k₁– k...Figure 11.5. Wave vector addition diagram for the process k₄ = 2k₂ – k₁....Figure 11.6. Schematic depiction of optical wavefront conjugation by degener...Figure 11.7. Induced refractive index grating is spatially shifted from the ...Figure 11.8. Moving intensity grating generated by two coherent incident las...Figure 11.9. Time‐dependent spatially moving index grating generated by two ...Figure 11.10. Matching the extraordinary refractive index n_e(θ_m) ...Figure 11.11. Nonlinear transverse phase shift and diffraction of a laser be...Figure 11.12. Radial intensity as a function of increasing input intensity s...Figure 11.13. Radial intensity distribution for increasing input intensity f...Figure 11.14. An experimental arrangement for achieving the optical limiting...Figure 11.15. Theoretical plot of the output and input laser pulses showing ...Figure 11.16. Coherent anti‐Stokes Raman scattering (CARS) involving the pum...Figure 11.17. (a) Wave vector phase matching of the pump wave , the generat...Figure 11.18. (a) Scattering of a polarized laser by director axis fluctuati...Figure 11.19. Calculated output e‐ and o‐wave as functions of input e‐wave p...Figure 11.20. Schematic depicting various direct self‐action ultrafast laser...Figure 11.21. Femtoseconds laser pulse self‐compression results were obtaine...

12 Chapter 12Figure 12.1. Experimental setup for optical limiting action using external s...Figure 12.2. Plot of detected output power versus input laser power. Insert ...Figure 12.3. Schematic depiction of a large dynamic range optical limiter co...Figure 12.4. Photograph of the transmitted laser beam (bright spot) and imag...Figure 12.5. Photographs of the transmission through the liquid crystal film...Figure 12.6. Experimental setup used in the first demonstration of spatial s...Figure 12.7. Computer simulations of the propagation in the (y‐z) plane of a...Figure 12.8. (a) Schematic of polarization rotation of a linearly polarized ...Figure 12.9. (a) Experimental setup for observing ultrafast polarization rot...Figure 12.10. Experimental setup for observing stimulated orientational scat...Figure 12.11. Recorded transmitted pump and signal as a function of input la...Figure 12.12. Stimulated o‐ to e‐ wave scattering. (a) Observed o‐wave power...Figure 12.13. (a) Phase diagram of the director angle coefficients A_i (in...Figure 12.14. (a) Photograph of the phase‐conjugated reconstructed image of ...Figure 12.15. Experimental setup for e‐o phase conjugation based on SOS. The...Figure 12.16. (a) Observed buildup dynamics of the e‐o phase conjugation sig...Figure 12.17. Theoretical plot of typical dynamics of self‐starting optical ...Figure 12.18. Oscilloscope traces of the time evolution of SSOPC signal as a...Figure 12.19. Experimental setup for incoherent to coherent image conversion...Figure 12.20. Experimental setup. Insert shows the planar twisted NLC film. ...Figure 12.21. Schematic depiction of experimental setup used to demonstrate ...Figure 12.22. Schematic depiction of total internal reflection ↔ transmissio...Figure 12.23. Experimental setup for observing the transmission‐TIR switchin...Figure 12.24. Oscilloscope traces of the transmitted IR laser pulse. Inciden...Figure 12.25. Oscilloscope traces of the transmitted CO₂ laser pulses throug...Figure 12.26. Schematic of TIR‐transmission switching/limiting device.Figure 12.27 Schematic depiction of the nonlinear fiber array placed in the ...Figure 12.28. Illustration of the extended interaction length provided by fi...Figure 12.29. Molecular energy levels of RSA materials, for example, C60 dop...Figure 12.30. (a) Limiting curve and (b) nonlinear transmission of C60‐ILC c...Figure 12.31. Photographs of the exit plane of the fiber array before, right...Figure 12.32. Molecular energy level scheme of the neat liquid L34.The symbo...Figure 12.33. Temporal propagation of a 120 μJ pulse through a 3 mm fiber ar...Figure 12.34. Limiting curves for liquid cored 3 mm fiber array (wavelength