physics-lasertech-2019-keynote

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allied
academies
April 15-16, 2019 | Frankfurt, Germany
Applied Physics & Laser, Optics and Photonics
International Conference on
Page 18
Materials Science and Nanotechnology | Volume: 3
CharlesVShankandhis teaminvented theColliding
Pulse Modelock (CPM) femtosecond laser at the
very beginning of the 1980’s. This started a rush on
the study of ultrafast phenomena. These studies
yielded very many new understandings in various
fields, of which, this talk will underline new results
in the fields of semiconductor physics, laser physics,
non-linear optics, and quantum optics. Did you know
that it takes silicon only 300 fs tomelt down when hit
by a short light pulse? This experimental observation
seeded the field of ultrafast electron dynamics
in semiconductors that in this talk will be further
highlighted by the measurement of the time it takes
to a pocket of out-of-equilibrium electrons to cool
down to a Boltzmann distribution.
It has been very early recognized that light absorption
saturates when the flux of photons impinging an
absorbing material exceeds the number of electrons
available in their energy ground state. But it needed
the use of short optical pulses, convoying little
energy, to demonstrate the saturation of the two-
photon absorption effect. This experiment was
performed in Cadmium Sulfide (CdS). It is also using
two-photon luminescence excitation in Rhodamine
B that the very existence of photonic jets generated
by micro-dielectric spheres was demonstrated. For
the first time, the non-linear effect of self-steepening
of an optical pulse was observed, when propagating
through a transparent material. In 2001, Bardou and
Boose theoretically demonstrated that the tunneling
probability of an electron can be enhanced by an ad
hoc pitch at the time it reflects on a potential barrier.
This new quantum effect was demonstrated using
an optical transposition of the effect using short
femtosecond pulses.
Speaker Biography
Charles Hirlimann was born in Paris in 1947. He majored in solid-state
physics and later acquired competence in laser physics. He pioneered
the use of femtosecond lasers applied to ultrafast spectroscopy of
solids being at the time assistant professor at University Pierre and
Marie Curie in Paris. He then joined CNRS and moved to the Institute
for Physics and Chemistry of Materials in Strasbourg (IPCMS) where he
initiated femtosecond studies. His interest spanned from the ultrafast
spectroscopy of electrons in semiconductors to basics researches in
non-linear optics. In the recent past, he served two years as a scientific
expert in nanomaterials for the European Commission in Brussels and
three years at the CNRS headquarters in Paris in charge of the European
scientific policy of CNRS and the International policy for Physics. He is
presently interested in the fast developments taking place in the field of
electron microscopy.
e:
Charles Hirlimann
IPCMS - CNRS, France
Pioneering days in ultrafast optics