705 research outputs found
Femtosecond resolution timing jitter correction on a TW scale Ti:sapphire laser system for FEL pump-probe experiments
Intense ultrashort pulse lasers are used for fs resolution pumpprobe
experiments more and more at large scale facilities, such as free electron
lasers (FEL). Measurement of the arrival time of the laser pulses and
stabilization to the machine or other sub-systems on the target, is crucial for
high time-resolution measurements. In this work we report on a single shot,
spectrally resolved, non-collinear cross-correlator with sub-fs resolution.
With a feedback applied we keep the output of the TW class Ti:sapphire
amplifier chain in time with the seed oscillator to ~3 fs RMS level for several
hours. This is well below the typical pulse duration used at FELs and supports
fs resolution pump-probe experiments. Short term jitter and long term timing
drift measurements are presented. Applicability to other wavelengths and
integration into the timing infrastructure of the FEL are also covered to show
the full potential of the device
Two-dimensional organization of a large number of stationary optical filaments by adaptive wave front control
We present an adaptive technique for the formation of multiple co-propagating and stationary filaments in a gaseous medium. Wavefront shaping of the initial beam is performed using a deformable mirror to achieve a complete two-dimensional control of the multi-spot intensity pattern in the laser focus. The spatial organization of these intensity spots yields reliable formation of up to five stable and stationary filaments providing a test bed for fundamental studies on multiple filamentatio
Design of a sub-13-fs, multi-gigawatt chirped pulse optical parametric amplification system
We present a design for phase-locked chirped pulse optical parametric amplification of ultra-short pulses based on Ti:sapphire. A realistic description is given by measuring the oscillator pulse (11.6fs, 4nJ) with SPIDER and numerically propagating it through the whole chirped pulse amplification system. The interaction is modeled with a full three-dimensional code and compression is ray-trace optimized to yield 12.7-fs, 98-μJ pulses with 1mJ of pump energy. The design is scalable in energy (e.g. 1mJ with 10-mJ pump) and is exclusively based on commercially available component
Field-driven femtosecond magnetization dynamics induced by ultrastrong coupling to THz transients
Controlling ultrafast magnetization dynamics by a femtosecond laser is
attracting interest both in fundamental science and industry because of the
potential to achieve magnetic domain switching at ever advanced speed. Here we
report experiments illustrating the ultrastrong and fully coherent light-matter
coupling of a high-field single-cycle THz transient to the magnetization vector
in a ferromagnetic thin film. We could visualize magnetization dynamics which
occur on a timescale of the THz laser cycle and two orders of magnitude faster
than the natural precession response of electrons to an external magnetic
field, given by the Larmor frequency. We show that for one particular
scattering geometry the strong coherent optical coupling can be described
within the framework of a renormalized Landau Lifshitz equation. In addition to
fundamentally new insights to ultrafast magnetization dynamics the coherent
interaction allows for retrieving the complex time-frequency magnetic
properties and points out new opportunities in data storage technology towards
significantly higher storage speed.Comment: 25 page
Fourier transform spectroscopy in the vibrational fingerprint region with a birefringent interferometer
We introduce a birefringent interferometer for Fourier transform (FT) spectroscopy in the mid-infrared, covering the vibrational fingerprint region (5-10 μm, 1000-2000 cm-1), which is crucial for molecular identification. Our interferometer employs the crystal calomel (Hg2Cl2), which combines high birefringence (ne-no≈0.55) with a broad transparency range (0.38-20 μm). We adopt a design based on birefringent wedges, which is simple and compact and guarantees excellent delay accuracy and long-term stability. We demonstrate FTIR spectroscopy, with a frequency resolution of 3 cm-1, as well as two-dimensional IR (2DIR) spectroscopy. Our setup can be extended to other spectroscopic modalities such as vibrational circular dichroism and step-scan FT spectroscopy
Control of high-order harmonic emission using attosecond pulse trains
We show that attosecond pulse trains are a natural tool to control strong field processes such as high-order harmonic generation. Coherently combining an attosecond pulse train with an IR driving field, we predict and experimentally confirm enhancement and spectral narrowing of the harmonic yield at photon energies around 90 eV. The use of an attosecond pulse train to seed the harmonic generation process replaces tunneling ionization with a single-photon ionization step, therefore permitting the manipulation of the time–frequency properties of high-order harmonic generation already at the single-atom level. © 2006 Taylor & Francis Group, LLC
Spatiotemporal Amplitude and Phase Retrieval of Bessel-X pulses using a Hartmann-Shack Sensor
We propose a new experimental technique, which allows for a complete
characterization of ultrashort optical pulses both in space and in time.
Combining the well-known Frequency-Resolved-Optical-Gating technique for the
retrieval of the temporal profile of the pulse with a measurement of the
near-field made with an Hartmann-Shack sensor, we are able to retrieve the
spatiotemporal amplitude and phase profile of a Bessel-X pulse. By following
the pulse evolution along the propagation direction we highlight the
superluminal propagation of the pulse peak
A Time- and Cost-Saving Method of Producing Rat Polyclonal Antibodies
Producing antibodies usually takes more than three months. In the present study, we introduce a faster way of producing polyclonal antibodies based on preparation of the recombinant oligopeptide as antigen followed by immunization of rats. Using this method, we produced antisera against two mouse proteins: ERGIC-53 and c-Kit. An expression vector ligated with a pair of complementary synthetic oligodeoxyribonucleotides encoding the protein was introduced into bacteria, and the recombinant oligopeptide fused with the carrier protein glutathione-S-transferase was purified. Wistar rats were immunized by injecting the emulsified antigen subcutaneously into the hind footpads, followed by a booster injection Âafter 2 weeks. One week after the booster, the sera were collected and examined for the antibody titer by immunohistochemistry. Antisera with 1600-fold titer at the maximum were obtained for both antigens and confirmed for their specificity by Western blotting. Anti-ÂERGIC-53 antisera recognized acinar cells in the sublingual gland, and anti-c-Kit antisera recognized spermatogenic and Leydig cells in the testis. These antisera were applicable to fluorescent double immunostaining with mouse monoclonal or rabbit polyclonal antibodies. Consequently, this method enabled us to produce specific rat polyclonal antisera available for immunohistochemistry in less than one month at a relatively low cost
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