Table of Contents i

Nederlandstalige Samenvatting v

English Summary ix

List of Tables xiii

List of Figures xv

List of Symbols and Abbreviations xxv

1 Introduction 1

1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2 Goal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2 Liquid Crystals 5

2.1 Material properties . . . . . . . . . . . . . . . . . . . . . . 5

2.2 Alignment . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.3 Electric and elastic properties . . . . . . . . . . . . . . . . 11

2.4 One-dimensional configurations . . . . . . . . . . . . . . 14

2.5 In-Plane switching . . . . . . . . . . . . . . . . . . . . . . 16

2.5.1 Director distribution . . . . . . . . . . . . . . . . . 17

2.5.2 One-dimensional approximation . . . . . . . . . . 18

3 Optical Transmission 23

3.1 Polarization of light . . . . . . . . . . . . . . . . . . . . . . 24

3.2 Jones Matrix Method . . . . . . . . . . . . . . . . . . . . . 26

3.2.1 Polarizer . . . . . . . . . . . . . . . . . . . . . . . . 29

3.2.2 Twisted nematic and anti-parallel rubbed . . . . . 29

3.2.3 In-plane switching mode . . . . . . . . . . . . . . 31

3.3 Rigorous CoupledWave Method . . . . . . . . . . . . . . 32

3.4 Reduced Grating Method . . . . . . . . . . . . . . . . . . 37

3.5 Simplified transmission model . . . . . . . . . . . . . . . 39

3.5.1 Transmission model . . . . . . . . . . . . . . . . . 39

3.5.2 Simulations . . . . . . . . . . . . . . . . . . . . . . 41

3.5.3 Experiments . . . . . . . . . . . . . . . . . . . . . . 46

4 Surface Anchoring 49

4.1 Weak and strong anchoring . . . . . . . . . . . . . . . . . 49

4.2 Modeling of weak anchoring . . . . . . . . . . . . . . . . 50

4.2.1 Expressions for the anchoring energy fs . . . . . . 51

4.2.2 Examples . . . . . . . . . . . . . . . . . . . . . . . 53

4.3 Weakly anchored in-plane switching mode . . . . . . . . 55

4.4 Measurement of the anchoring strength . . . . . . . . . . 59

4.4.1 Field-off techniques . . . . . . . . . . . . . . . . . 59

4.4.2 Field-on techniques . . . . . . . . . . . . . . . . . . 60

4.5 Flow and memory anchoring . . . . . . . . . . . . . . . . 61

4.6 Weak anchoring experiments . . . . . . . . . . . . . . . . 62

4.6.1 Cell preparation . . . . . . . . . . . . . . . . . . . . 62

4.6.2 Microscope observations . . . . . . . . . . . . . . . 63

a) Static microscope observation . . . . . . 63

b) Influence of memory alignment . . . . . 66

c) Memory alignment in the 3-GPS cell . . 67

d) Memory alignment in the BCB cell . . . 70

e) Switching and relaxation for FC4430 . . 74

4.6.3 Transmission measurements . . . . . . . . . . . . 79

a) Average electro-optic measurements . . 79

b) Estimation of the azimuthal anchoring

strength . . . . . . . . . . . . . . . . . . . 80

5 Liquid Crystal Device with a Rotatable Director 85

5.1 Structure of the reconfigurable wave plate . . . . . . . . . 86

5.2 Operating principle . . . . . . . . . . . . . . . . . . . . . . 87

5.3 Director simulations . . . . . . . . . . . . . . . . . . . . . 90

5.3.1 Simulated director distribution . . . . . . . . . . . 91

5.3.2 Purpose of the dielectric layer . . . . . . . . . . . . 95

a) Simplifiedmodel for the influence of the dielectric layer . . . . . . . . . . . . . . . 96

b) Mirror plane perpendicular to the aver-age electric field . . . . . . . . . . . . . . 100

5.3.3 Switching times of the device . . . . . . . . . . . . 103

5.3.4 Multistable wave plate . . . . . . . . . . . . . . . . 106

5.4 Optical simulations . . . . . . . . . . . . . . . . . . . . . . 107

5.4.1 General considerations . . . . . . . . . . . . . . . . 107

a) Regular rectangular mesh . . . . . . . . 107

b) Diffraction orders on a rectangular and a hexagonal lattice . . . . . . . . . . . . . 109

c) Transmissive and reflective mode . . . . 111

5.4.2 Transmissive mode . . . . . . . . . . . . . . . . . . 112

a) Crossed polarizers . . . . . . . . . . . . . 112

b) Influence of the applied voltage . . . . . 117

c) Transmission as a function of time . . . . 120

5.4.3 Reflective mode . . . . . . . . . . . . . . . . . . . . 122

a) Improvement of the JMM algorithm . . 122

b) Reconfigurable wave plate . . . . . . . . 125

5.5 Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . 127

5.5.1 Production process of the reconfigurablewave plate127

a) Device design . . . . . . . . . . . . . . . 128

b) Device processing . . . . . . . . . . . . . 129

5.5.2 Measurements . . . . . . . . . . . . . . . . . . . . 132

a) Distinguishing the three different driv-ing configurations . . . . . . . . . . . . . 133

b) Control of the average director alignment 135

c) Influence of the applied potential . . . . 137

d) 360◦ in-plane rotation of the director . . 140

e) Improvements to the device . . . . . . . 141

5.6 Applications for the new liquid crystal device . . . . . . . 143

5.6.1 Hexagonal device with rubbed alignment layers . 144

5.6.2 Electric field driven alignment direction . . . . . . 144

5.6.3 Intermediate director alignment . . . . . . . . . . 144

6 Conclusion 147

6.1 Achievements . . . . . . . . . . . . . . . . . . . . . . . . . 147

6.2 Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148

Bibliography 151

List of Publications 165

Index 16