Applications for Science

Particle acceleration & photo-injector
Improving
the quality of electron beams seeding large particle accelerator is the
main goal of laser photo-injector. A femtosecond laser beam is hitting a
photo-cathode thus providing electron packets with tight properties
control. The ALPHA products line is offering specific option to adapt on
Linear Accelerator with interface to photocathode and jitter control.

VUV and X Ray generation
Any
body emits light waves when heated. The higher the temperature, the
shorter the wavelength of the wave is. Plasma can reach extremely high
temperatures, especially when excited with femtosecond laser pulses.
Consequently very short wavelengths are emitted like Very Ultra Violet
or X rays.

The ALPHA 10 and 100 Series is perfectly suited for this applications.

Wake field acceleration
A
Terawatt/Petawatt femtosecond pulse is sent through plasma. The
electric field in the pulse wake is so intense that it can be used to
accelerate the plasma electrons at relativistic speeds. This application
requires highly intense electric fields and ALPHA 10 Series is
particularly appropriate.

High harmonic and attosecond pulse generation
The
interaction of rare earth gases or metal with ultrashort pulses gives
rise to the generation of High harmonics through the well known three
step model. A train of attosecond pulses is generated by this technique.
If the interaction is achieved with a few-cycle pulse with controled
Carrier Envelope phase a single attosecond pulse can be isolated.

ALPHA kHz Series is the ideal tool to use for such processes.

THALES
lasers are particularly adapted for pumping of different coherent light
sources, such as Ti:Sa amplifiers, Optical Parametric Oscillators and
Amplifiers (OPO/OPA) and Dye Lasers.

Ultrafast Ti:Sa amplifiers pumping
Ultrafast laser systems based on Ti:Sa crystals are widely used for
many applications. They require pumping by green lasers of high beam
quality and stability. The SHG output of THALES nanosecond lasers
(ATLAS+, GAÏA HP, GAÏA, SAGA, JADE 2, ETNA, ETNA HP) provides
outstanding specifications for such requirements.

OPA/OPO Pumping
OPO/OPG/OPA pumping requires pump beams of low divergence and high
beam pointing stability. According to the wavelength output of OPO/OPA,
fundamental or harmonic wavelengths of THALES lasers can be used.
Depending on the pulse duration, THALES nanosecond lasers (OPO/OPA) or
femtosecond lasers (OPG/OPA) can be used.

Dye Cell Pumping
Dye lasers can be a handy way to obtain a particular wavelength as a
wide choice of dyes is available. Different pump wavelengths (fundamntal
or harmonics) may be necessary as each dye has different absorption and
emission properties.

Time resolved pump-probe spectroscopy
Time
resolved spectroscopy is used to study photo induced reactions. A
femtosecond laser beam (pump beam) is sent on the sample and brings the
matter to the state that has to be studied (plasma, high energy state).
After this shot, a second beam (probe beam) is sent through the sample
and the temporal evolution of the state can be measured by absorption,
fluorescence with high time accuracy.

ALPHA 100, ALPHA kHz are highly suited for this application.

Laser Induced Breakdown Spectroscopy (LIBS)
LIBS is a non destructive spectroscopy method to analyze the chemical
composition of a material: The laser beam is focused on the sample. The
power density at focus is sufficient to ionize and vaporize the
material. This ionzed state is called plasma. When the remaining
electrons of the ions return to lower energy levels, photons are
emitted.

The wavelength of each photon is characteristic of the
elements contained in the plasma. The emission spectrum of the plasma
yields several lines whose intensity gives information about the nature
and the concentration of each specie.

SAGA, JADE 2, ETNA, ALPHA 100 and ALPHA kHz are recommended for LIBS application.

Fluorescence measurements

Laser Induced Fluorescence (LIF)
LIF
is an imaging technique to analyze species distribution in fluids. A UV
laser beam is sent on the sample. The specie absorbs the incident light
and the electrons of the molecular bounds reach a higher energy level.
After a short time (fluorescence time), the excited electrons return to
their low energy state and photons are emitted (this is called
fluorescence). Each emitted photon is specific to the specie that
absorbed the incident laser beam and the specie distribution can be
imaged on a camera or quantified with an appropriate detection
equipment.

SAGA is well adapted to this application.

Multi photon excitation
Multi photon excitation is also based on fluorescence, but uses a non
linear phenomenon. A high peak power laser pulse is focused on the
sample. Because of the high photon density, several low energy photons
can be absorbed by one electron to reach a higher energy level. This is
called multi photon absorption. Consequently, no specific photon
wavelength is required to excite the sample. Moreover, multi photon
absorption only occurs at the focal spot, and because of the very short
pulse duration, heat has no time to propagate through the sample, so
damage is limited to a very small area.Once absorption has been
completed, the process remains similar to LIF: the electrons return to
their fundamental state and emit photons. It is then possible to image
the sample or analyse the emission spectrum.