# 08- Fluctuation-dominated materials for advanced photonics

**Source**: https://www.cs.tum.de/spp1839/projects/2nd-period-2018-2021/08.html
**Parent**: https://www.cs.tum.de/spp1839/projects.html

The
main aim of this project is to develop nanostructured materials for
novel photonic applications in which a well-designed disorder induces
huge fluctuations of local electromagnetic fields. In these structures,
the nonlinear response of the ‘hot spots’ with largest fields will
dominate and, on average, strongly increase the nonlinear response of
the sample. This approach may lead to a whole new class of
‘fluctuation-dominated materials’ -- for photonics, but mutatis mutandis
for other wave-based technologies as well. For two model systems,
metallic nanoporous gold nanoparticles (‘nanosponges’) and dielectric
nanostructured silicon nano-needles (‘nanograss’), we established
field-enhancement factors and electromagnetic mode confinements that
come close to the best values achievable with state-of-the-art top-down
nanotechnology, e.g., in nano antenna produced via focusion-beam
lithography. Experimental near-field scanning spectroscopy and ultrafast
photoemission microscopy of a single gold nanosponge prepared within
this project resolved long-lived localized plasmonic hot spots with
sub-10 nm resolution in excellent agreement with theoretical
calculations.

 

The
present successful close cooperation of material science and
nanofabrication with, on the one hand most advanced optical
characterization methods, and on the other hand a detailed theoretical
analysis and modelling of the relevant near-field optics and solid-state
physics will be continued with the following goals:

(i) nanofabrication of materials with optimized disorder for further enhanced field-fluctuations based on a deeper understanding\
 of hot-spot formation;

(ii)
new experiments for space- and timeresolved studies of the locally
enhanced non-linear response and further increase of the latter;

(iii)
design, fabrication and investigation of hybrid materials where small,
typically atom- or molecule-sized emitters with suitable quantum-optical
properties are, e.g., infiltrated into nanosponge pores. The coupling
of quantum-emitters to hot-spot modes allows optical functionalities far
surpassing those of the constituents.

Finally, we plan

(iv)
to enter completely unchartered territory by the study of the
interaction of our fluctuation-dominated materials with strong Terahertz
fields which will modulate the interaction of the long-lived,
ultra-localized hot spots.

 

It
should be emphasized, that the paradigm of ‘fluctuation-dominated
materials’ has been confirmed for systems as different as metallic
nanosponges and dielectric silicon nanograss. This indicates that the
underlying physical mechanisms will be present in many systems with
tailored disorder, making the SPP 1839 the ideal context and fruitful
environment for the planned research and cooperation.

## Contributors

Prof. Christoph Lienau

|  |
| --- |
|  |

Dr. Juemin Yi

|  |
| --- |
|  |

Prof. Erich Runge

|  |
| --- |
|  |

Sebastian Bohm

|  |
| --- |
|  |

Martí Bosch

|  |
| --- |
|  |

Prof. Peter Schaaf

|  |
| --- |
|  |

Hongmei Wang

|  |
| --- |
|  |

[Go back to project listing](../../projects.html)