Active Plasmonics And Tuneable Plasmonic Metamaterials PDF Download

The past two decades has seen considerable interest in Plasmonics and Metamaterials (P & MM); two intertwined fields of research. The interest is driven by matured nano-fabrication and characterization technologies and the limitations facing traditional photonics. While light cannot be squeezed beyond the diffraction limit, extreme light-matter interactions enabled the manipulation of light at length-scales much shorter than the wavelength of light. The prospects of plasmonics and metamaterials include subwavelength nano-photonic interconnects and circuits, light harvesting and solar energy, enhancement of linear and non-linear optical processes, sensing, ultrathin optical displays, structural coloring and quantum information and communication.The field of plasmonics studies all aspects related to structures that can support plasmons; oscillations of free electrons in metals. From this perspective, one can consider plasmonics as the field of metal photonics that studies light-metal interaction in the optical range. Metals are not subject to the diffraction limit since light is confined by coupling to electron oscillations, or plasmons, in the metal. Electromagnetic (EM) field can thus be confined on length scales comparable to the dimensions of the metallic nanostructure. On the other hand, Metamaterials are engineered materials that enjoy optical properties and functionalities beyond what natural materials can provide. Usually metamaterials are composed of different materials or structures that interact with light resulting in an emergent property due to the interplay of all the component materials and/or structures. In the optical range (visible and NIR), metamaterials heavily rely on metallic nano-structures as they allow for strong light-matter interaction at the sub-wavelength range. The strong field localization, however, comes at a cost; electrons scatter and absorb the localized field at the femtosecond timescale. The problem of strong optical losses in plasmonics and metamaterials with metal components is the major obstacle in applications and devices that require high efficiency, e.g. perfect lenses, clocking devices, and plasmonic transistors and interconnects. The confinement-loss tradeoff is what defines the future of P & MM [1]. As the field of plasmonics and metamaterials mature, the possible applications are adapting to the fundamental limitations of metal photonic materials. In addition to traditional, low efficiency applications of plasmonics, e.g., surface enhanced Raman spectroscopy (SERS), other applications that does not require high efficiency, e.g., metal enhanced fluorescence and plasmonic rulers are promising. Furthermore, losses can be desirable in applications that require strong light absorption and/or heat generation such as thermo-photovoltaics, solar energy generation, thermal emitters, optical absorbers and structural coloring, cancer photo-thermal therapy, and heat assisted magnetic recording.Between low efficiency applications and applications where losses are desirable, one can envision a wide array of applications where the benefits of field confinement out-weigh the losses. In particular, an important consequence of strong field confinement is that changes in the surrounding EM environment can induce a strong change in the optical properties of a P & MM system. Such changes would result in an ultrafast, sub-nanosecond, response that can be useful in many applications. An active P & MM system is one where the existence of an external mechanical, electrical, thermal or optical stimulus modifies the system’s light-matter interaction. This thesis aims to explore various active P & MM systems. To design an active system one needs first to create a passive system that enjoys a certain feature which is a function of the EM environment. By introducing a change in the EM environment, we obtain a measurable change in the passive feature. The first part deals with active plasmonics, particularly, gain-plasmon dynamics. We study the ultrafast dynamics of gain-plasmon interaction and reveal an active plasmonic system where the spontaneous emission rate of a quantum emitter is dynamically modulated. The main objective of this thesis is to slightly uncover the richness of P & MM despite the existence of strong losses and beyond the traditional or loss-based applications. The second part of the thesis deals with metamaterials that exhibit tunable, strong to perfect light absorption and their application in hydrogen gas sensing as an example for their optical activity.