Development of a VMI spectrometer: first photoelectron spectra obtained with a plasma-based 32.6nm soft x-ray laser.

The “DIRAM” group of the Institut des Sciences Moléculaires d’Orsay (ISMO) led by Annie Klisnick is developing cutting edge technics to fully characterise the pulse temporal structure of modern XUV sources (plasma based soft x-ray laser, X-ray free electron lasers, high order harmonics…). With the support of the OPT2X project, they have build a Velocity Mapping Imager

or VMI. In this type of photoelectron spectrometer, a soft x-ray pulse photo ionises atoms from a gas jet. The photoelectrons are collected and focussed on a micro-channel plate. In this device, the impact points of electrons with the same kinetic energy are forming a circle, as shown in the present figure. During this experiment, the ISMO group took benefit from the high monochromaticity of a  32.6 nm soft x-ray laser to test the VMI and optimise the energy resolution: the thinner the circle, the higher the resolution. This figure of merit is import for future applications. Coupled to an auxilliary IR or THz beam, this device will be a fantastic tool to measure the XUV pulse duration in multiple pulses mode (“cross-correlation”) or even in single shot (“streaking”).


Courtesie of Tatyana Sinyakova, Amira Gharbi, Cédric Bommes, Denis Cubaynes and Annie Klisnick

Double pulse quasi-collinear high harmonic generation scheme

We have investigated high harmonic generation in an argon gas cell driven by two femtosecond laser pulses separated by a variable delay ranging from 500 fs to 100 ps. Experiments were performed at the LASERIX IR-EUV facility using an amplified 10 Hz CPA Ti:Sapphire laser system on a beamline delivering 50 fs pulses at 800 nm with energy up to 15 mJ. In the case of a non-zero time delay we studied the optimal conditions for equilibrated double pulse generation despite perturbation of the generating medium induced by the first pulse. We showed how high harmonic double pulse generation varies with the gas pressure, the excitation energy, the delay and the relative polarization between the two laser pulses. Due to the very high spatial overlap of the two generating IR beams throughout the gas cell, results obtained here can reasonably be extrapolated to perfectly collinear pulses. Besides, we confirmed that the observed behavior does not depend on the relative polarization states, parallel or crossed, of the two IR generating pulses. Moreover, the spectra of the two EUV pulses remain identical. These three properties are of great interest for plasma-based soft X-ray laser seeding experiments aiming at probing the gain and polarization dynamics of the amplifier stage. This type of study gives also insight into the physics of very high repetition rate harmonics, above 1 GHz.

S. Daboussi et al., Double pulse quasi-collinear high harmonic generation scheme as a tool for X-ray laser plasma gain probing, Applied.Phys. B,100,(2012

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

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 soft X-ray laser into the amplifier target was realized by a spherical mirror. The results show amplification of the seed soft 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.
Article : Gain lifetime measurement of a Ni-like Ag soft X-ray laser, Optics Express, Vol. 20, Issue 23, pp. 25391-25399 (2012), doi : 10.1364/OE.20.02539

Temporal characterization of a picosecond EUV laser pumped in grazing incidence

Our users and collaborators from ISMO recently published their work on the temporal characterization of our picosecond extreme ultraviolet laser pumped in grazing incidence. They have investigated the shot-to-shot reproducibility of the pulse duration, as well as its behaviour as a function of several pumping parameters.

Article : Temporal characterization of a picosecond extreme ultraviolet laser pumped in grazing incidence. L. Meng et al. Appl. Phys. Lett. 101, 141125 (2012); doi: 10.1063/1.4757878

2012 Aimé Cotton award recipient is Sophie Kazamias

Sophie Kazamias associate professor at Université Paris Sud has just been awarded 2012 Aimé Cotton Prize from french Physics Society for “her works in the development of coherent sources in the extreme UV (EUV), from high harmonic generation to EUV plasma based laser”. Sophie Kazamias received a pHD in 2003 for the optimization of high order harmonic sources for nonlinear optics in the EUV at LOA. Since 2003 she has carried on her research on LASERIX facility and taught physic and optics courses in the Physic department of the Université Paris Sud

LASERIX team presents three papers at ICXRL 2012

LASERIX team presents 3 papers in Paris during the ICXRL 2012

Harmonic generation and soft-x-ray laser with LASERIX : source development, applications and advanced diagnosis” , Olivier Guilbaud et al.
High harmonic generation driven by non-collinear double pulse” , Sameh Daboussi et al.
Regenerative cavity tuning for efficient soft-x-ray laser operation” , Olivier Delmas et al.