Tuning the high-order harmonic lines of a Nd:Glass laser for soft x-ray laser seeding

Taking advantage of the non-adiabatic blue-shift of high-order harmonics generated by a fixed frequency Nd:Glass laser system, we are able to report more than 50 % coverage of the XUV spectral range between 18 nm and 35 nm. The generated harmonic lines are capable of seeding Ni-like Y, Zr and Mo soft x-ray lasers and others.

High-brilliance double-stage soft x-ray laser pumped by multiple pulses applied in grazing incidence

A new compact scheme for a double-stage seeded x-ray laser is demonstrated. This laser is offering greatly improved beam quality and brilliance making it a useful tool for applications.

An Improved Double-Pulse Non-Normal Incidence Pumping Geometry for Transient Collisionally Excited Soft X-Ray Lasers

An optimized pumping geometry for transient collisionally excited soft X-ray lasers is presented, similar to the geometry proposed by [1]. In contrast to usual approaches, where a nanosecond pre-pulse is assumed to provide the optimal plasma preparation and a picosecond pulse performs the final heating- and excitation process, two pulses of equal duration in the range around 10 picoseconds are applied. Both pulses are produced in the front end of the CPA pump laser. They are focused onto the target with the same spherical mirror under non-normal incidence geometry, optimized for efficient traveling wave excitation for the main-pulse. A first experiment was performed on Ni-like palladium (14…

Short-wavelength soft-x-ray laser pumped in double-pulse single-beam non-normal incidence

We demonstrated a $7.36$ nm Ni-like samarium soft-x-ray laser, pumped by $36$ J of a neodymium:glass chirped-pulse amplification laser. Double-pulse single-beam non-normal-incidence pumping was applied for efficient soft-x-ray laser generation. In this case, the applied technique included a single-optic focusing geometry for large beam diameters, a single-pass grating compressor, traveling-wave tuning capability, and an optimized high-energy laser double pulse. This scheme has the potential for even shorter-wavelength soft-x-ray laser pumping.

Towards high photon-number soft x-ray lasers

We present an experimental design to independently pump two soft X-ray laser media suitable for a seed-amplifier configuration. Both the seed and the amplifier target are operated in the TCE scheme utilizing the DGRIP technique with its intrinsic travelling wave excitation. Controlled injection of the seed X-ray laser into the amplifier medium is realized via a spherical XUV mirror. The experimental design is perfectly appropriate for benchmarking combined simulations of the ARWEN and DeepOne code. A first experiment at the PHELIX laser utilizing this scheme has been conducted, demonstrating signs of amplification and allowing for the direct measurement of the gain life time of a Ni-like si…

Versatile High-Energy and Short-Pulse Operation of PHELIX

PHELIX (Petawatt High Energy Laser for Heavy Ion Experiments) is a hybrid Ti:Sapphire / Nd:Glass laser system using large aperture amplifiers from the former Nova and Phebus laser systems at Livermore and Limeil, respectively, designed to offer pulse energies in access of 2 kJ and output power in the petawatt range. It is aiming mainly on combined experiments in plasma physics [2] and atomic physics [3] together with the GSI accelerator facility, and in preparation for the new FAIR facility for antiproton and ion research. Both nanosecond and sub-picosecond pulses can be supplied. Presently pulse energies up to 500 J are used, at pulse durations between 2 and 25 ns. Compressed pulses down t…

A beamline for x-ray laser spectroscopy at the experimental storage ring at GSI

By combining an x-ray laser (XRL) with a heavy-ion storage ring, precision laser spectroscopy of the fine-structure splitting in heavy Li-like ions will be possible. An initial study has been performed to determine the feasibility of a first experiment at the experimental storage ring at GSI in Darmstadt, which also has great potential for the experiments planned for FAIR. We plan to perform a unique, direct and precise measurement of a fine-structure transition in a heavy Li-like ion. Such a measurement will test state-of-the-art atomic structure calculations in strong fields. This endeavour will require that the existing infrastructure is complemented by a dedicated beamline for the XRL. …

Tuning of High-Order Harmonics for Soft X-Ray Laser Seeding

Within this work we present results of an experimental campaign studying the influence of the adiabatic and non-adiabatic blue shift on high-order harmonic (HH) radiation spectra. The results demonstrate that we are able to spectrally tune the HH radiation to cover more than 50% of the spectrum between 17 nm and 35 nm, paving the way to performing injection-seeded soft X-ray laser (SXRL) experiments with Mo, Zr and Y.

Laser driven parametric amplification in the xuv and soft-x-ray spectral range

We present the first experimental realization of a new x-ray laser scheme based on strong-field parametric amplification of high-order harmonic radiation. With a simple semi-classical model, we can identify the most important experimental parameters, the spectral range and the small signal gain in gases. Using a single amplifier stage a small signal gain of 8000 has been obtained in Argon for the spectral range of 40-50 eV, using 350 fs, 7 mJ pulses at 1.05 µm. In Helium, we observed a small signal gain of 280 around 300 eV using 6 fs, 1.5 mJ pulses at 800 nm.

Laser-driven amplification of soft X-rays by parametric stimulated emission in neutral gases

The high-order harmonics of short laser pulses created in a nonlinear medium are a useful source of extreme-ultraviolet and soft-X-ray radiation. A newly discovered phenomenon that amplifies this emission even further could improve the efficiency of short-wavelength light sources.

Laser driven X-ray parametric amplification in neutral gases—a new brilliant light source in the XUV

Abstract In this paper we present the experimental setup and results showing a new type of strong-field parametric amplification of high-order harmonic radiation. With a simple semi-classical model, we can identify the most important experimental parameters, the spectral range and the small signal gain in gases. Using a single stage amplifier, a small signal gain of 8000 has been obtained in argon for the spectral range of 40–50 eV, using 350 fs, 7 mJ pulses at 1.05 μm. An outlook for an experiment employing a double stage gas system will be given.

Characterization of a 10Hz double-pulse non-normal incidence pumped transient collisional Ni-like molybdenum soft x-ray laser for applications

Stable and reliable operation of a nickel-like molybdenum transient collisional soft x-ray laser at 18.9 nm demonstrated and studied with a 10Hz Ti:sapphire laser system proves the suitability of the double-pulse non-normal incidence pumping geometry for table-top high repetition soft x-ray lasers and broadens the attractiveness of x-ray lasers as sources of coherent radiation for various applications. X-ray laser emission with pulse energies well above 1 μJ is obtained for several hours at 10Hz repetition-rate without re-alignment under optimized double pumping pulse parameters including energy ratio, time delay, pulse duration and line focus width.

Reply to 'The super-quadratic growth of high-harmonic signal as a function of pressure'

Gain lifetime measurement of a Ni-like Ag soft X-ray laser

International audience; Experimental results of a two-stage Ni-like Ag soft X-ray laser operated in a seed-amplifier configuration are presented. Both targets were pumped applying the double-pulse grazing incidence technique with intrinsic travelling wave excitation. The injection of the seed X-ray laser into the amplifier target was realized by a spherical mirror. The results show amplification of the seed X-ray laser and allow for a direct measurement of the gain lifetime. The experimental configuration is suitable for providing valuable input for computational simulations. (C) 2012 Optical Society of America

Strong field amplification of XUV: phase matching aspects

The dependence of the yield of high-order harmonic generation (HHG) on several important experimental parameters has been successfully modeled in the last 20 years by taking into account the single atom response and propagation effects. We extended this description by adding a stimulated emission process and named it x-ray parametric amplification (XPA). Beyond the super-quadratic increase of the XUV signal, which can be explained only in a limited pressure range by HHG theory, other observed characteristics like exponential growth, gain narrowing, strong blue-shift, beam divergence, etc. and their dependence on laser intensity and gas pressure can be explained accurately only by the new XP…