OPTICS OF
COMPLEX SYSTEMS
Photonic crystals |
| Periodic modulation of the refractive index on scales
comparable to
the wavelength produces crystal-like structures where the propagation
of light is strongly influenced by interference effects. As a result
the dispersion relation can be modified and gaps can be opened in the
band diagram. Read more |
Quasicrystals |
| Deterministic but non-periodic structures have many
features
similar to crystal-like (periodic) systems. Nevertheless there are some
striking differences like the fractal nature of the spectrum
of
most quasi-crystals. Read more |
Random lasing |
| In disordered systems light performs multiple
scattering and may
take a long time before it exit the structure. In the presence of gain
light can experience more amplification than losses creating a
cavity-less laser action. Read
more |
Anderson localization |
| For sufficiently strong disorder the independent
scattering
approximation fails and the interference effects become important. In
this regime the diffusion process comes to a halt and the eigenstates
of the system become exponentially localized. Read more |
Lévy flights |
 When
the step lenght distribution in the multiple scattering regime doesn't
have a finite variance the transport is dominated by extremely large
jumps and the system becomes superdiffusive. Read more |
Experimental setups and techniques
Optical gating - By looking at the sum-frequency generated between a ultra-fast signal and a (known) gate signal with adjustable delay it is possible to measure the time profile of the signal with femtosecond accuracy. Read more
Backscattering cone - The constructive interference beetween counterpropagating paths give rise to a cone of enhanced reflection whose shape strongly depends on the mean free path. Read more
Near field microscopy - Near-field scanning optical microscopy (SNOM) is a technique that enables non-diffraction limited imaging and spectroscopy of a sample that is simply not possible with conventional optical imaging. Read more
Confocal microscopy -
Confocal microscopy use a spatial filter to eliminate out-of-focus
light whose thickness exceeds the immediate plane of focus. Read
more
Numerical tools - Whenever the analythical description of a certain system is not available or it's not feasible a numerical approach (like Finite Difference Time Diomain or Monte Carlo simulations) can give some insight in the problem. Read more