Optical Characterization of Plasmonic Nanostructures: Near-Field Imaging of the Magnetic Field of Light (eBook)

Denitza Denkova completed her Bachelor (2008) and Master (2010) studies in Physics at Sofia University, Bulgaria. During her studies she also worked part-time as an engineer at Melexis, a microelectronics company. In a joint project between these institutions she studied specific malfunctions in microelectronics circuits via various structural, optical and electrical characterization techniques, including the development of a cathodoluminescence add-on to a scanning electron microscope. Denitza then moved to KU Leuven, Belgium to further develop her interest in nanoscale characterization as a PhD. There she developed and applied a novel approach for imaging the magnetic field of light with nanoscale resolution, in the context of characterization of plasmonic and metamaterial devices.

Supervisor’s Foreword 7
Abstract 9
Acknowledgments 12
Contents 17
Abbreviations 20
Symbols 21
1 Introduction 23
1.1 Surface Plasmon Resonances in Metal Nanoparticles 23
1.1.1 The Underlying Physics 23
1.1.2 Plasmonics: Application Highlights 26
1.1.3 Optical Characterization of Plasmonic Devices 28
1.2 Scanning Near-Field Optical Microscopy (SNOM) 30
1.2.1 The Diffraction Limit 30
1.2.2 Principles of Sub-wavelength Optical Microscopy 37
1.2.3 Basic Configuration and Practical Realizations 38
1.2.4 Artifacts and Challenges 45
1.3 SNOM for Imaging the Magnetic Field of Light 46
1.3.1 Imaging the Electromagnetic Field Components by SNOM 47
1.3.2 Fundamental Challenges in Imaging the Magnetic Field of Light 48
1.3.3 Experimental Setup for Imaging the Magnetic Field of Light 50
References 51
2 Imaging the Magnetic Near-Field of Plasmon Modes in Bar Antennas 56
2.1 Introduction 56
2.2 Results and Discussion 58
2.2.1 Individual Probe and Sample Characterization 59
2.2.2 Probe-Sample Coupling: Imaging of the |Hy|2 Near-Field Distribution of an l=3 Plasmon Mode in a Gold Bar 60
2.2.3 Imaging of the |Hy|2 Near-Field Distribution of Different Plasmon Modes in a Gold Bar 64
2.2.4 Plasmon Dispersion Relation Obtained by SNOM 64
2.3 Conclusions 67
2.4 Methods 68
2.4.1 Sample Fabrication 68
2.4.2 FDTD Simulations 68
2.4.3 Electric and Magnetic Field Profiles at the Apex of the Probe 69
References 70
3 A Near-Field Aperture-Probe as an Optical Magnetic Source and Detector 74
3.1 Introduction 74
3.2 Results and Discussion 75
3.2.1 Hollow-Pyramid Aperture Probe as a tangential Hy Dipole Source: Intuitive Physical Justification 75
3.2.2 Correspondence Between the Fields of the Hollow-Pyramid Probe and a tangential Hy Dipole: Simulations 78
3.2.3 Scanning of the Probe Over a Sample 79
3.2.4 Experimental Evidence for Equivalence of Collection and Illumination Mode SNOM 81
3.3 Conclusions 82
References 83
4 Magnetic Near-Field Imaging of Increasingly Complex Plasmonic Antennas 84
4.1 Introduction 84
4.2 Results and Discussion 86
4.2.1 Simple Antennas 87
4.2.2 Complex Antennas Consisting of Assembled Bars 89
4.3 Conclusions 93
4.4 Methods 94
4.4.1 Sample Preparation 94
4.4.2 Simulations 94
4.5 Supporting Information 94
4.5.1 Simulation of the |Hy|2 Near-Field Map of an Elementary Horizontal Bar 96
4.5.2 Simulation of the |Hy|2 Near-Field Map of an Elementary Vertical Bar 96
4.5.3 Simulation of the |Hy|2 Near-Field Map of Complex Antennas 96
4.5.4 Electromagnetic Field Components of a Representative Complex Antenna 98
References 99
5 Conclusions and Outlook 101
5.1 Conclusions 101
5.2 Outlook 103
Curriculum Vitae 105