Twisted Photons: Applications of Light with Orbital Angular Momentum

Preface XI

List of Contributors XV

Color Plates XIX

1 The Orbital Angular Momentum of Light: An Introduction 1
Les Allen and Miles Padgett

1.1 Introduction 1

1.2 The Phenomenology of Orbital Angular Momentum 4

References 9

2 Vortex Flow of Light: ‘‘Spin’’ and ‘‘Orbital’’ Flows in a Circularly Polarized Paraxial Beam 13
Aleksandr Bekshaev and Mikhail Vasnetsov

2.1 Introduction 13

2.2 Spin and Orbital Flows: General Concepts 14

2.3 Transverse Energy Flows in Circularly Polarized Paraxial Beams 15

2.4 Orbital Rotation without Orbital Angular Momentum 21

2.5 Conclusion 22

References 23

3 Helically Phased Beams, and Analogies with Polarization 25
Miles Padgett

3.1 Introduction 25

3.2 Representation of Helically Phased Beams 26

3.3 Exploiting the Analogous Representations of Spin and Orbital Angular Momentum 27

3.4 Conclusions 33

References 34

4 Trapping and Rotation of Particles in Light Fields with Embedded Optical Vortices 37
Michael Mazilu and Kishan Dholakia

4.1 Introduction 37

4.2 Laguerre–Gaussian Light Beams 38

4.3 Origin of Optical Torques and Forces 41

4.4 Optical Vortex Fields for the Rotation of Trapped Particles 51

4.5 Optical Vortex Fields for Advanced Optical Manipulation 57

4.6 Conclusions 61

Acknowledgments 62

References 62

5 Optical Torques in Liquid Crystals 67
Enrico Santamato and Bruno Piccirillo

5.1 The Optical Reorientation and the Photon Angular Momentum Flux 70

5.2 Dynamical Effects Induced in Liquid Crystals by Photon SAM and OAM Transfer 78

5.3 Conclusions 89

References 90

6 Driving Optical Micromachines with Orbital Angular Momentum 93
Vincent L.Y. Loke, Theodor Asavei, Simon Parkin, Norman R. Heckenberg, Halina Rubinsztein-Dunlop, and Timo A. Nieminen

6.1 Introduction 93

6.2 Symmetry, Scattering, and Optically Driven Micromachines 93

6.3 Experimental Demonstration 96

6.4 Computational Optimization of Design 102

6.5 Conclusion 113

References 113

7 Rotational Optical Micromanipulation with Specific Shapes Built by Photopolymerization 117
Péter Galaja, Lóránd Kelemen, László Oroszi, and Pál Ormos

7.1 Introduction 117

7.2 Microfabrication by Photopolymerization 118

7.3 Light-Driven Rotors, Micromachines 121

7.4 Integrated Optical Motor 128

7.5 Angular Trapping of Flat Objects in Optical Tweezers Formed by Linearly Polarized Light 131

7.6 Torsional Manipulation of DNA 134

7.7 Conclusion 138

Acknowledgment 139

References 139

8 Spiral Phase Contrast Microscopy 143
Christian Maurer, Stefan Bernet, and Monika Ritsch-Marte

8.1 Phase Contrast Methods in Light Microscopy 143

8.2 Fourier Filtering in Optical Imaging 144

8.3 Spiral Phase Fourier Filtering 146

8.4 Implementation and Performance 151

8.5 Conclusions 152

References 152

9 Applications of Electromagnetic OAM in Astrophysics and Space Physics Studies 155
Bo Thidé, Nicholas M. Elias II, Fabrizio Tamburini, Siavoush M. Mohammadi, and José T.Mendonça

9.1 Introduction 155

9.2 Ubiquitous Astronomical POAM 156

9.3 Applications of POAM in Astronomy 158

9.4 Applications of POAM in Space Physics 165

9.A. Appendix: Theoretical Foundations 169

References 175

10 Optical Vortex Cat States and their Utility for Creating Macroscopic Superpositions of Persistent Flows 179
Ewan M. Wright

10.1 Introduction 179

10.2 Optical Vortex Cat States 181

10.3 Macroscopic Superposition of Persistent Flows 189

10.4 Summary and Conclusions 195

References 195

11 Experimental Control of the Orbital Angular Momentum of Single and Entangled Photons 199
Gabriel Molina-Terriza and Anton Zeilinger

11.1 Introduction to the Photon OAM 199

11.2 Control of the OAM State of a Single Photon 201

11.3 Control of the OAM State of Multiple Photons 203

11.4 Applications in Quantum Information 207

11.5 Discussion 209

11.6 Conclusion 211

References 211

12 Rotating Atoms with Light 213
Kristian Helmerson and William D. Phillips

12.1 Introduction 213

12.2 Orbital Angular Momentum of Light 213

12.3 The Mechanical Effects of Light 214

12.4 Rotating Bose–Einstein Condensates 215

12.5 Measuring the Rotational Motion of the Atoms 220

12.6 Generating Other Rotational States of Atoms 224

12.7 Supercurrents 230

12.8 Conclusion 231

Acknowledgments 232

References 232

Index 237