Ultrafast all-optical switching
Switching the optical properties of nanophotonic structures all-optically provides the ability to dynamically
manipulate such systems as light propagates through them.
The increasing interest in all-optical switching is due
to the inherent fastness of the process, which promises both new developments in information technology and a novel
control of fundamental processes in, e.g., cavity quantum electrodynamics.
Of major interest are microcavities since they allow the storage of light for a certain amount of time in a small volume
thereby increasing the interaction of light and matter.
There are two main switching mechanism being exploited, free-carrier switching and switching using the electronic Kerr effect
leading to ultimate fast shift of the cavity resonance and to a chnage in the frequency and bandwidth of the stored photons.
Near-field optics and especially near-field scanning optical microscopy (NSOM) has become very popular again in recent years.
This is due to the increased attention to nanosized photonic structures, such as photonic crystals, waveguides, and cavities.
With NSOM one gains information of the structure (topography) with the high lateral resolution of an atomic force microscope
(AFM) while at the same time one has a sub-wavelength optical resolution due to the nanosized probe.
It is therefore possible to retrieve information on the influence of the structure (periodic, ordered, or disordered) on the
light field traveling inside, not only in the linear interaction but also in the non-linear interaction regime.
Furthermore, the influence of applied external fields on the light propagation (electro- and magneto-opics) can be studied
with high accuracy.
The excitation and propagation of surface plasmons at the interfaces of nanostructured
metallic films are responsible for their observed special optical properties, such as the enhanced optical transmission.
Moreover, patterning such subwavelength hole arrays into ferromagnetic thin films is an effective
way to alter and engineer the magnetic response of the film, such as coercivity, remanence, and anisotropy.
The combination of both effects is subject of magneto-plasmonics,
where the excitation of surface plasmons in a magnetic field strongly influences the magneto-optic response of the material.
Lab-on-a-chip (LOC) technology has gained a lot of momentum since it was first proposed and developed in the late 1980s.
The main interests for LOC focus thereby around the fields of chemical analysis, biomedical analysis, personal care, as well as DNA detection and polymerization.
Yet, there is a gap between the small-scale research needs and the large scale production of such chips.
Our focus lies in the development of low-cost LOC devices as sensors for detection of low-concentration pollutants in, e.g., water waste.
In that respect changes in material and methods had to be developed.