Plasmonics and Ultrafast NanoOptics

Plasmonics

Fundamental plasmonics research within the group ranges from the control and excitation of surface plasmons on complex nanostructured surfaces, to understanding plasmonic characteristics on the femtosecond time scale.
In addition to fundamental surface plasmon research, the application of plasmonic phenomena into technologies, e.g. solar cell enhancement and bio-diagnostic tools, is also addressed.

For a brief introduction and history of surface plasmon research, click here.


Plasmonics Research Team Members

Dr Dominic Zerulla (PI)
Gillian Doyle, Stephen Crosbie and Patxi Lopez-Barbera (PhD Students)


Research Topics

Plasmons on Nanostructured Surfaces

The design and architecture of nanostructures for the purpose of controlling and manipulating SPP dynamics is currently a focal point of research, driven by the predicted impact that plasmonic components will have on many future technologies.
Tailor designed nanostructured surfaces offer the possibility to both excite SPPs, and control some of the characteristics, such as excitation, propagation, localisation, reradiation, polarisation, etc.
Using FIB and e-beam lithography fabrication techniques, we design nanostructured surfaces to examine and control various SPP properties including plasmon mediated polarisation twisting, plasmon focusing, and plasmon interference effects.

FemtoSecond Plasmon Dynamics

Time scales associated with SPPs vary from 100’s of attoseconds to 100’s of nanoseconds. The lower limit is a theoretical limit defined by the inverse spectral width of a broadband plasmonic resonance, and is one of the fastest time scales in optics. However, a more general feature of their time scale is their typical propagation lifetime, which for the visible and IR regimes ranges from 10’s to 100’s of femtoseconds.
In the experimental plasmonics community, as of yet, little experimental output has come from examining plasmons propagating at a planar metal / dielectric interface at the fs scale. The reason for this is apparent from the difficulty in making accurate measurements on a suitable time scale. However, understanding these ultraquick processes is of key importance to the field of nanoplasmonics, and could have potential applications in, for example, ultrafast computations, and data control and storage on the nanoscale.
In our current experiments, using a Ti:Sa laser to excite propagating plasmons on both nanostructured and planar metal / dielectric interfaces, we employ a combination of intensity autocorrelation, optical spectroscopy, FROG and GRENOUILLE techniques to further our understanding of ultrafast SPP dynamics, and also to shed light on other fundamental plasmonic process such as their excitation dynamics.

Magneto Plasmonics

MagnetoPlasmonics (or Spinplasmonics) is a field of nanotechnology combining spintronics and plasmonics. It is the study and application of the interaction of SPPs with magnetically ordered systems. The most elementary spinplasmonic device consists of a bilayer structure made from ferromagnetic and diamagnetic metals. Alternatively, it may be possible to directly excite SPPs on Nickel, at or below telecommunication frequencies. In such architectures, properties of SPPs could be manipulated by applying a weak external magnetic field, changing the spin state of the ferromagnetic layer. This would instill a spin barrier, with electrons (of the SP electron density oscillation) of an aligned spin state allowed to cross the barrier, but those with a different spin state being impeded. Essentially, switching operations are performed with the electrons spin, and then coupled out as a light signal. Spinplasmonic devices potentially have the advantages of high speed, miniaturization, low power consumption, and multifunctionality.

Mie Plasmons

This section will be added shortly.

Plasmon Enhancement for Spectroscopy Studies

This section will be added shortly.

Plasmonic Enhanced Solar Cells

Surface Plasmons offer the possibility to confine or store electromagnetic radiation in the vicinity of a plasmon active layer (i.e. nanostructured metal / dielectric halfspace). In this project, computational and experimental investigations on the implementation of such a layer into the architecture of a dye sensitised solar cell (DSSC)  will be made. Specifically, the focus is to generate a broadband, polarisation and angle independent, efficient plasmon active layer; that can be cost efficiently integrated into an inverted DSSC.


Research Methods

Our dark lab's are equipped with a wide range of tools for the experimental examination of surface plasmon phenomena.
Along with a selection of optics and laser light sources (200nm to 1500nm, pulsed (15 fs to 10ns) or CW lasers over a range of optical powers), the lab is equipped with a wide range of detection, manipulation and imaging tools including: sSNOM, PEEM, PSTM, FROG, GRENOUILLE, autocorrelation, optical tweezers, AFM, STM, SEM, TEM and a wide range of spectrometers and optical intensity detectors.
Additionally, sample preparation and fabrication techniques available include FIB, thermal and e-beam evaporation, and cleaning facilities.