Active magnetoplasmonics for nanoscale distances sensing

Magnetoplasmonics is an emerging field within nano-photonics that operates with the combination of propagating or localized surface plasmons and magnetism. Active and adaptive magnetoplasmonic components that are capable of controlling light on the nanoscale with external weak magnetic fields are envisioned to push the development of integrated photonic circuits, high-density data storage, or the advanced schemes for bio- and chemo-sensing. In these components plasmon-enhanced and controlled magneto-optical activity creates a new way of active control of plasmonic devices.In this thesis we investigate the role of localized surface plasmons on magneto-optical activity and demonstrate how magnetoplasmonics can be employed in the optical detection of nanoscale distances. Plasmon rulers are an emerging concept in which the strong near-field coupling of plasmon nanoantenna elements is employed to obtain structural information at the nanoscale. We introduce an active magnetoplasmonic ruler that provides active operation and nanoscale distances reading with the figure-of-merit substantially exceeding the one of traditional plasmon rulers. We combine nanoplasmonics and nanomagnetism to conceptualize a magnetoplasmonic dimer nanoantenna that would be able to report nanoscale distances while optimizing its own spatial orientation. The latter constitutes an active operation, in which a dynamically optimized optical response per measured unit length allows for the measurement of small and large nanoscale distances with about two orders of magnitude higher precision than current state-of-the-art plasmon rulers

Active magnetoplasmonics for nanoscale distances sensing

Magnetoplasmonics is an emerging field within nano-photonics that operates with the combination of propagating or localized surface plasmons and magnetism. Active and adaptive magnetoplasmonic components that are capable of controlling light on the nanoscale with external weak magnetic fields are envisioned to push the development of integrated photonic circuits, high-density data storage, or the advanced schemes for bio- and chemo-sensing. In these components plasmon-enhanced and controlled magneto-optical activity creates a new way of active control of plasmonic devices.In this thesis we investigate the role of localized surface plasmons on magneto-optical activity and demonstrate how magnetoplasmonics can be employed in the optical detection of nanoscale distances. Plasmon rulers are an emerging concept in which the strong near-field coupling of plasmon nanoantenna elements is employed to obtain structural information at the nanoscale. We introduce an active magnetoplasmonic ruler that provides active operation and nanoscale distances reading with the figure-of-merit substantially exceeding the one of traditional plasmon rulers. We combine nanoplasmonics and nanomagnetism to conceptualize a magnetoplasmonic dimer nanoantenna that would be able to report nanoscale distances while optimizing its own spatial orientation. The latter constitutes an active operation, in which a dynamically optimized optical response per measured unit length allows for the measurement of small and large nanoscale distances with about two orders of magnitude higher precision than current state-of-the-art plasmon rulers

Nanoscale magnetophotonics

This Perspective surveys the state-of-the-art and future prospects of science and technology employing the nanoconfined light (nanophotonics and nanoplasmonics) in combination with magnetism. We denote this field broadly as nanoscale magnetophotonics. We include a general introduction to the field and describe the emerging magneto-optical effects in magnetoplasmonic and magnetophotonic nanostructures supporting localized and propagating plasmons. Special attention is given to magnetoplasmonic crystals with transverse magnetization and the associated nanophotonic non-reciprocal effects, and to magneto-optical effects in periodic arrays of nanostructures. We give also an overview of the applications of these systems in biological and chemical sensing, as well as in light polarization and phase control. We further review the area of nonlinear magnetophotonics, the semiconductor spin-plasmonics, and the general principles and applications of opto-magnetism and nano-optical ultrafast control of magnetism and spintronics

Dynamically Tunable Optical Cavities with Embedded Nematic Liquid Crystalline Networks

Tunable metal–insulator–metal (MIM) Fabry–P\ue9rot (FP) cavities that can dynamically control light enable novel sensing, imaging\ua0and display applications. However, the realization of dynamic cavities incorporating stimuli-responsive materials poses a significant engineering challenge. Current approaches rely on refractive index modulation and suffer from low dynamic tunability, high losses, and limited spectral ranges, and require liquid and hazardous materials for operation. To overcome these challenges, a new tuning mechanism employing reversible mechanical adaptations of a polymer network is proposed, and dynamic tuning of optical resonances is demonstrated. Solid-state temperature-responsive optical coatings are developed by preparing a monodomain nematic liquid crystalline network (LCN) and are incorporated between metallic mirrors to form active optical microcavities. LCN microcavities offer large, reversible and highly linear spectral tuning of FP resonances reaching wavelength-shifts up to 40\ua0nm via thermomechanical actuation while featuring outstanding repeatability and precision over more than 100 heating–cooling cycles. This degree of tunability allows for reversible switching between the reflective and the absorbing states of the device over the entire visible and near-infrared spectral regions, reaching large changes in reflectance with modulation efficiency ΔR\ua0=\ua079%

Magnetoplasmonic design rules for active magneto-optics

Light polarization rotators and non-reciprocal optical isolators are essential building blocks in photonics technology. These macroscopic passive devices are commonly based on magneto-optical Faraday and Kerr polarization rotation. Magnetoplasmonics - the combination of magnetism and plasmonics - is a promising route to bring these devices to the nanoscale. We introduce design rules for highly tunable active magnetoplasmonic elements in which we can tailor the amplitude and sign of the Kerr response over a broad spectral range

Electrical and Optical Characterization of InP Nanowire Ensemble Photodetectors

Photodetectors are semiconductor devices that can convert optical signals into electrical signals. There is a wide range of photodetector applications such as fiber optics communication, infrared heat camera sensors, as well as in equipment used for medical and military purposes. Nanowires are thin needle-shaped structures made of semiconductor materials, e.g. gallium arsenide (GaAs), indium phosphide (InP) or silicon (Si). Their small size, well-controlled crystal structure and composition as well as the possibility to fabricate them monolithically on silicon make them ideally suited for sensitive photodetectors with low noise. In this project, Fourier Transform Infrared (FTIR) Spectroscopy is used to investigate the optical characteristics of InP nanowire-based PIN photodetectors. The corresponding electrical characteristics are also measured using very sensitive instrumentation. A total of 4 samples consisting of processed nanowires with 80 nm diameter but different density and length have been examined. The experiments were conducted from 78K (-196oC) to room temperature 300K (27oC). The spectrally resolved photocurrent and current-voltage (IV) curves (in darkness & under illumination) for different temperatures have been studied and analyzed. The samples show excellent IV performance with very low leakage currents. The photocurrent scales with the number of nanowires, from which we conclude that most photocurrent is generated in the substrate. Spectrally resolved photocurrent data, recorded at different temperatures, display strong absorption in the near-infrared region with interesting peaks that reveal the underlying optical processes in the substrate and nanowires, respectively. The nature of the absorption peaks is discussed in detail. This study is an important step towards integration of optically efficient III-V nanoscale devices on cheap silicon substrates for applications e.g. on-chip optical communication and solar cells for energy harvesting

All-Dielectric and Magnetoplasmonic Nanoantenna Surfaces for the Dynamic Chiroptics

Optical platforms enabling the dynamic real-time control of the fundamental properties of light at visible and near-infrared wavelengths are the essential components for the future optical devices. Combining magnetic materials with the metallic and all-dielectric nano-optics enables a simultaneous enhancement and mutual control of their magneto-optical and chiro-optical properties. Here we examine hybrid nanoantennas made of Si and ferromagnetic metal developing magnetically-controlled chiroptical surfaces

Magnetoplasmonic Design Rules for Active Magneto-Optics

Light polarization rotators and nonreciprocal optical isolators are essential building blocks in photonics technology. These macroscopic passive devices are commonly based on magneto-optical Faraday and Kerr polarization rotation. Magnetoplasmonics, the combination of magnetism and plasmonics, is a promising route to bring these devices to the nanoscale. We introduce design rules for highly tunable active magnetoplasmonic elements in which we can tailor the amplitude and sign of the Kerr response over a broad spectral range