Spontaneous emission inside hyperbolic metamaterials

Student thesis: Doctoral ThesisDoctor of Philosophy


Spontaneous emission is a fundamental manifestation of quantum mechanics and is strongly modified by the material environment in which the emitters are placed. Achieving the control of radiative and non-radiative transitions is of great importance for applications ranging from biosensing and optical communications to quantum technologies. The design of nanostructured media with tailored electromagnetic properties opens up a route for controlling the emission rate and the non-radiative energy transfer via the engineering of the local density of optical states. In this thesis, the influence of a gold nanorod-based hyperbolic metamaterial on the spontaneous emission and energy transfer between emitters located within the metamaterial is investigated. Hyperbolic metamaterials have emerged as a flexible and powerful platform for these purposes providing a high local density of states due to their peculiar mode structure. In a theoretical and experimental analysis, it is shown that the emission process in a nanorod-based hyperbolic metamaterial is strongly affected by its nonlocal response, thus impacting the emission dynamics and leading to a broadband 30-fold reduction of the emitters lifetime spanning the whole visible spectral range. To further emphasize the importance of the mode structure of the metamaterial in the emission process, an almost 50-fold enhancement of the spontaneous emission coupled to a waveguided mode of the metamaterial is demonstrated. The emission of a long lifetime Ruthenium complex involving spin-forbidden dipolar transitions is also studied. Rate enhancements far beyond the predictions of the standard electromagnetic local density of states description are observed, reaching 1000-fold near a gold film and higher inside the metamaterial. The influence of the local density of states on non-radiative energy transfer is presented, leading to more than 10-fold increase of the FRET rate inside the metamaterial. These results demonstrate the potential of highly tuneable hyperbolic metamaterials for the control of spontaneous emission and energy transfer, highlighting the capability of such materials for the design of enhanced and fast light sources.
Date of Award1 Dec 2017
Original languageEnglish
Awarding Institution
  • King's College London
SupervisorAnatoly Zayats (Supervisor), Nicolas Olivier (Supervisor) & Wayne Dickson (Supervisor)

Cite this