# 14 - Fluctuation-dominated materials for advanced photonics

**Source**: https://www.cs.tum.de/spp1839/projects/1st-period-2015-2018/14.html
**Parent**: https://www.cs.tum.de/spp1839/projects.html

The aim of this project is to develop
nanostructured materials that utilize optical near-field interactions
and disorder-induced fluctuations of local electromagnetic fields to
achieve novel photonic functionality. While Nature uses disordered
nanostructured materials since millions of years, e.g., in the wings of
colorful butterflies, mankind has learned only recently how to
nanostructure metal to detect a single molecule. Tailoring disorder in
nanostructured dielectric and metallic materials to optimize the
coupling of electromagnetic fields to suitably chosen quantum emitters
(laser dyes, J-aggregates, quantum dots,etc.) is mostly unchartered
territory; even though recent progress in materials nanofabrication,
optical spectroscopy and theoretical solid state physics provides, in
principle, all necessary tools. Within this project, experts from these
fields join forces to

1. enhance local electromagnetic field
   fluctuations by tailoring disorder in selected quasi-two-dimensional
   and quasi-three-dimensional metallic and dielectric nanostructures and
2. insert quantum emitters such that their nonlinear response yields novel photonic functionality.

Such
system systems are inherently robust since environment-induced
detunings between certain pairs of emitters and local cavities are
compensated by other functionally equivalent pairs. The project focuses
on three kinds of disordered systems:

1. arrays of dielectric nanoneedles made of technologically relevant transparent semiconductor oxides and nitrides,
2. percolating metal films with nano-sized voids and islands and
3. nanoporous gold nanoparticles obtained by de-alloying Au-Ag nanoparticles.

These
samples will be covered or infiltrated by optically nonlinear
material. Besides designing potentially even economically attractive
photonic materials, the project is expected to substantially deepen our
microscopic understanding of light-matter coupling on the nanoscale,
the physics underlying disorder-induced light and surface plasmon
localization and - more generally - of fluctuation-dominated systems.
The time structure of individual localized electromagnetic modes will
be probe in a recently developed ultrafast SH microscope in Oldenburg
whereas their spatial mode profile is mapped with 20-nm resolution in a
new near-field microscope. The theoretical analysis of
disorder-induced localization phenomena will be based on the expertise
of the Ilmenau theoretical physics group for optical manifestations of
Anderson localization and for coupled exciton-plasmon systems.
Tailor-designed disordered samples will be provided by the Ilmenau
material science group. A close interdisciplinary collaboration and
continued feedback among the teams will ensure the fabrication of
samples with tailor-made disorder and novel or at least superior
photonic functionality.

## Contributors

- [Prof. Christoph Lienau](https://www.uni-oldenburg.de/uno/ "Opens internal link in current window")
- [Prof. Erich Runge](https://www.tu-ilmenau.de/theophys1/ "Opens internal link in current window")
- [Prof. Peter Schaaf](https://www.tu-ilmenau.de/wt-wet/ "Opens internal link in current window")
- Dr. Dong Wang
- Wenye Rao

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