Designer nanostructures for visible light
11:00 - 12:00
MPI for Intelligent Systems, Stuttgart
CFEL (Bldg. 99)
Seminar Room III, EG.080
There exists a size difference between molecules and visible wavelengths. Nanofabrication techniques can be adopted to obtain designed meta-molecules or meta-materials, with interesting optical properties.
Most nanostructures are chemically synthesized, but they tend to be
highly symmetrical and achiral. A recent advance in physical vapor
deposition, known as Glancing Angle Deposition, permits the growth of
chiral thin films and chiral nanocolloids. The optical properties of
plasmonic nanohelices that can be produced on wafer scale samples, offer
very strong polarization dependence, i.e. the circular optical activity
can be precisely tailored by the shape of the nanohelices from the UV
to the IR. This is useful to obtain meta-materials which can be
programmed to have an index of refraction that can change from n ~ +1.1
down to n ~ –0.2, depending on the ellipticity of the incident light.
magnetic metals, thin films with both large natural and magnetic
optical activity can be obtained that permit the detection of
magneto-chiral dichroism in absorption for visible light through arrays
of ferromagnetic nanohelices at room conditions, with perturbing
magnetic fields < 10–1 T.