21 research outputs found
Condensation in disordered lasers: theory, 3D+1 simulations and experiments
The complex processes underlying the generation of a coherent-like emission
from the multiple-scattering of photons and wave-localization in the presence
of structural disorder are still mostly un-explored. Here we show that a single
nonlinear Schroedinger equation, playing the role of the Schawlow-Townes law
for standard lasers, quantitatively reproduces experimental results and
three-dimensional time-domain parallel simulations of a colloidal laser system.Comment: 4 pages, 5 figure
Microdissection of human chromosomes by a laser microbeam
A laser microbeam apparatus, based on an excimer laser pumped dye laser is used to microdissect human chromosomes and to isolate a single chromosome slice
Glassy behavior of light
We study the nonlinear dynamics of a multi-mode random laser using the
methods of statistical physics of disordered systems. A replica-symmetry
breaking phase transition is predicted as a function of the pump intensity. We
thus show that light propagating in a random non-linear medium displays glassy
behavior, i.e. the photon gas has a multitude of metastable states and a non
vanishing complexity, corresponding to mode-locking processes in random lasers.
The present work reveals the existence of new physical phenomena, and
demonstrates how nonlinear optics and random lasers can be a benchmark for the
modern theory of complex systems and glasses.Comment: 5 pages, 1 figur
Time-resolved and state-selective detection of single freely falling atoms
We report on the detection of single, slowly moving Rubidium atoms using
laser-induced fluorescence. The atoms move at 3 m/s while they are detected
with a time resolution of 60 microseconds. The detection scheme employs a
near-resonant laser beam that drives a cycling atomic transition, and a highly
efficient mirror setup to focus a large fraction of the fluorescence photons to
a photomultiplier tube. It counts on average 20 photons per atom.Comment: 6 pages, 7 figure
Magneto-optical trap for metastable helium at 389 nm
We have constructed a magneto-optical trap (MOT) for metastable triplet
helium atoms utilizing the 2 3S1 -> 3 3P2 line at 389 nm as the trapping and
cooling transition. The far-red-detuned MOT (detuning Delta = -41 MHz)
typically contains few times 10^7 atoms at a relatively high (~10^9 cm^-3)
density, which is a consequence of the large momentum transfer per photon at
389 nm and a small two-body loss rate coefficient (2 * 10^-10 cm^3/s < beta <
1.0 * 10^-9 cm^3/s). The two-body loss rate is more than five times smaller
than in a MOT on the commonly used 2 3S1 -> 2 3P2 line at 1083 nm. Furthermore,
we measure a temperature of 0.46(1) mK, a factor 2.5 lower as compared to the
1083 nm case. Decreasing the detuning to Delta= -9 MHz results in a cloud
temperature as low as 0.25(1) mK, at small number of trapped atoms. The 389 nm
MOT exhibits small losses due to two-photon ionization, which have been
investigated as well.Comment: 11 page