H. Merdji

H. Merdji
École Polytechnique · Département de Physique

Professor
Strong field quantum optics. Attosecond physics. Nanophotonics. Plasmonics. Nanoscale X-ray diffractive imaging.

About

183
Publications
23,388
Reads
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5,097
Citations
Citations since 2016
55 Research Items
1796 Citations
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
Additional affiliations
October 2011 - March 2022
CEA saclay
Position
  • Research Director
Description
  • Head of the Ultrafast Nanophotonics Group
March 2007 - February 2012
Stanford University
Position
  • Visiting Physicist

Publications

Publications (183)
Article
An interesting property of high harmonic generation in solids is its laser polarization dependent nature which in turn provides information about the crystal and band structure of the generation medium. Here we report on the linear polarization dependence of high-order harmonic generation from a gallium arsenide crystal. Interestingly, we observe a...
Preprint
Full-text available
An interesting property of high harmonic generation in solids is its laser polarization dependent nature which in turn provides information about the crystal and band structure of the generation medium. Here we report on the linear polarization dependence of high-order harmonic generation from a gallium arsenide crystal. Interestingly, we observe a...
Article
We demonstrate a method to image an object using a self-probing approach based on semiconductor high-harmonic generation. On the one hand, ptychography enables high-resolution imaging from the coherent light diffracted by an object. On the other hand, high-harmonic generation from crystals is emerging as a new source of extreme-ultraviolet ultrafas...
Preprint
We demonstrate a method to image an object using a self-probing approach based on semiconductor high-harmonic generation. On one hand, ptychography enables high-resolution imaging from the coherent light diffracted by an object. On the other hand, high-harmonic generation from crystals is emerging as a new source of extreme-ultraviolet ultrafast co...
Article
The surge of interest in nonperturbative high-harmonic generation in solids has been driven by the appeal of compact solid-state extreme ultraviolet sources and the prospect of untangling the material properties through high-harmonic generation response to strong fields. The traditional assumption is that the brighter, lower-order harmonics are pur...
Article
Full-text available
Enhancing ultrafast nonlinear processes at a nanometer scale has the potential of creating novel nano-sources of energetic photons or particles useful for many applications, especially for embedded diagnostics. In this work, we investigate the plasmonic amplification of the third harmonic generation (THG) from a metal-dielectric-metal (MDM) nano-re...
Article
High harmonic generation (HHG) in crystals has revealed a wealth of perspectives such as all-optical mapping of the electronic band structure , ultrafast quantum information, and the creation of all-solid-state attosecond sources. Significant efforts have been made to understand the microscopic aspects of HHG in crystals, whereas the macroscopic ef...
Article
Full-text available
La génération d’harmoniques laser d’ordre élevé dans les cristaux semiconducteurs est une nouvelle source de rayonnement ultra-bref (femtoseconde à attoseconde) cohérent et de courte longueur d’onde (de l’ordre de quelques dizaines de nanomètres) à très haute cadence. Outre la versatilité de cette source pour les applications, offerte notamment par...
Article
Full-text available
High-order harmonic generation (HHG) from crystals is emerging as a new ultrashort source of coherent extreme ultraviolet (XUV) light. Doping the crystal structure can offer a new way to control the source properties. Here, we present a study of HHG enhancement in the XUV spectral region from an ionic crystal, using dopant-induced vacancy defects,...
Preprint
Full-text available
High harmonic generation (HHG) in crystals has revealed a wealth of perspectives such as all-optical mapping of the electronic band structure, ultrafast quantum information and the creation of novel all-solid-state attosecond sources. Significant efforts have been made to understand the microscopic aspects of HHG in crystals, whereas the macroscopi...
Article
Spatial coherence is an impactful source parameter in many applications ranging from atomic and molecular physics to metrology or imaging. In lensless imaging, for example, it can strongly affect the image formation, especially when the source exhibits shot-to-shot variations. Single-shot characterization of the spatial coherence length of a source...
Article
Full-text available
On the basis of real-time ab initio calculations, we study the nonperturbative interaction of two-color laser pulses with MgO crystal in the strong-field regime to generate isolated attosecond pulses from high-harmonic emissions from MgO crystal. In this regard, we examine the impact of the characteristics of the incident pules, such as its shape,...
Preprint
On the basis of real-time ab initio calculations, we study the non-perturbative interaction of two-color laser pulses with MgO crystal in the strong field regime to generate isolated attosecond pulse from high-harmonic emissions from MgO crystal. In this regard, we examine the impact of incident pulse characteristics such as its shape, intensity, a...
Article
Full-text available
Recent technological advances in attosecond science hold the promise of tracking electronic processes at the shortest space and time scales. However, the necessary imaging methods combining attosecond temporal resolution with nanometre spatial resolution are currently lacking. Regular coherent diffractive imaging, based on the diffraction of quasi-...
Article
Solids irradiated by energetic photons can be eroded in two modes, depending on the radiation intensity. High average, low-peak power sources, e.g., synchrotron radiation and high-order harmonics, induce desorption of the material at a low etch rate. In contrast, high-peak-power radiation from extreme ultraviolet and x-ray lasers usually causes a m...
Article
Full-text available
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Preprint
The study of the non-linear response of matter to high electric fields has recently encompassed harmonic generation in solids at near-infrared (NIR) driving wavelengths. Interest has been driven by the prospect of ultrafast signal processing and all-optical mapping of electron wave-functions in solids. Engineering solid-state band structures to con...
Article
Full-text available
The study of the non-linear response of matter to high electric fields has recently encompassed harmonic generation in solids at near-infrared (NIR) driving wavelengths. Interest has been driven by the prospect of ultrafast signal processing and all-optical mapping of electron wave-functions in solids. Engineering solid-state band structures to con...
Article
Full-text available
Today, 3D imaging techniques are emerging, not only as a new tool in early drug discovery but also for the development of potential therapeutics to treat disease. Particular efforts are directed towards in vivo physiology to avoid perturbing the system under study. Here, we assess non-invasive 3D lensless imaging and its impact on cell behavior and...
Preprint
High-order harmonic generation (HHG) from crystals offers a new source of coherent extreme ultraviolet (XUV) attosecond radiation. The process is extremely sensitive to the band structure and symmetries. Here, we tailor the high-order harmonic radiation by engineering the band structure of the bulk material using dopant-induced vacancy defects. We...
Article
Full-text available
Degenerate plasmas, in which quantum effects dictate the behavior of free electrons, are ubiquitous on earth and throughout space. Transitions between bound and free electron states determine basic plasma properties, yet the effects of degeneracy on these transitions have only been theorized. Here, we use an x-ray free electron laser to create and...
Preprint
Full-text available
Recent advances in the field of attosecond science hold the promise of tracking electronic processes at the shortest space and time scales. Imaging methods that combine attosecond temporal with nanometer spatial resolution are currently out of reach. Coherent diffractive imaging is based on the diffraction by a sample of a quasi-monochromatic illum...
Preprint
The ability to gain insights into the 3D properties of artificial or biological systems is often critical. However, 3D structures are difficult to retrieve at low dose and with extremely fast processing, as most techniques are based on acquiring and computing hundreds of 2D angular projections. This is even more challenging with ultrashort X-rays w...
Article
Full-text available
We report on the carrier-envelope phase (CEP) stabilization of a Yb-doped fiber amplifier system delivering 30 μJ pulses at 100 kHz repetition rate. A single-shot, every-shot measurement of the CEP stability based on a simple f-2f interferometer is performed, yielding a CEP standard deviation of 320 mrad rms over 1 s. Long-term stability is also as...
Article
Full-text available
Recovering the three-dimensional (3D) properties of artificial or biological systems using low X-ray doses is challenging as most techniques are based on computing hundreds of two-dimensional (2D) projections. The requirement for a low X-ray dose also prevents single-shot 3D imaging using ultrafast X-ray sources. Here we show that computed stereo v...
Poster
Full-text available
In the present study, second harmonic generation (SHG) in Sapphire, Fused Silica (FS), thin ZnO crystal, pure MgO and Chromium (Cr) doped MgO crystals is investigated. We explore SHG dependence on the orientation angle between the crystal and laser polarization. Furthermore, the impact of modifying the electronic structure on the yield of SHG has b...
Poster
Full-text available
High harmonic generation (HHG) in solids is a promising route towards compact and bright sources of extreme ultraviolet (XUV) pulses, owing to the higher electron density in solids. By driving various solids with strong infrared (IR) electric fields, a way to unveil the microscopic mechanism of the HHG process, and the electronic structure of the s...
Article
Full-text available
The enhancement and control of non-linear phenomena at a nanometer scale has a wide range of applications in science and in industry. Among these phenomena, high-harmonic generation in solids is a recent focus of research to realize next generation petahertz optoelectronic devices or compact all solid state EUV sources. Here, we report on the reali...
Preprint
Full-text available
We report on the CEP stabilization of an Yb-doped fiber amplifier system delivering 30 microjoules, 100 fs pulses at 100 kHz repetition rate. A single shot, every shot, measurement of the CEP stability based on a simple f-2f interferometer is performed, yielding a CEP standard deviation of 320 mrad rms over 1 s. Long-term stability is also assessed...
Preprint
Degenerate plasmas, in which quantum effects dictate the behavior of free electrons, are ubiquitous on earth and throughout space. Transitions between bound and free electron states determine basic plasma properties, yet degeneracy effects on these transitions have only been theorized. Here, we use an x-ray free electron laser to create and charact...
Article
Light beams carrying orbital angular momentum (OAM) have led to stunning applications in various fields from quantum information to microscopy. We examine OAM from the recently observed high-harmonic generation (HHG) in semiconductor crystals. HHG from solids could be a valuable approach for integrated high-flux short-wavelength coherent light sour...
Preprint
Full-text available
The enhancement and control of non-linear phenomena at a nanometer scale has a wide range of applications in science and in industry. Among these phenomena, high-harmonic generation in solids is a recent focus of research to realize next generation petahertz optoelectronic devices or compact all solid state EUV sources. Here, we report on the reali...
Preprint
Full-text available
Light beams carrying orbital angular momentum (OAM) have led to stunning applications in various fields from quantum information to microscopy. In this letter, we examine OAM from the recently discovered high-harmonic generation (HHG) in semiconductor crystals. HHG from solids could be a valuable approach for integrated high-flux short-wavelength c...
Article
We present measurements of photon absorption by free electrons as a solid is transformed to plasma. A femtosecond x-ray free-electron laser is used to heat a solid, which separates the electron and ion heating time scales. The changes in absorption are measured with an independent probe pulse created through high-order-harmonic generation. We find...
Article
Full-text available
We experimentally demonstrate the use of subwavelength optical nanoantennas to assist a direct nanoscale ablation using the ultralow fluence of a Ti:sapphire oscillator through the excitation of surface plasmon waves. The mechanism is attributed to nonthermal transient unbonding and electrostatic ablation, which is triggered by the surface plasmon-...
Conference Paper
We show the amplification of non-perturbative harmonics by local field enhancement in 3D semiconductors. Then, we investigate high harmonic generation in free standing 2D graphene. Finally, we propose routes for spatio-temporal coupling using 3D nanostructured semiconductors.
Conference Paper
This paper reviews our recent results on the development of ultrafast (100 ps – 100 fs) fiber lasers at 2 μm wavelength and their applications from mid-infrared spectroscopy to UV generation in graphene and micromachining of polymers.
Conference Paper
We show the amplification of non-perturbative harmonics by local field enhancement in 3D semiconductors. Then, we investigate high harmonic generation in free standing 2D graphene. Finally, we propose routes for spatio-temporal coupling using 3D nanostructured semiconductors.
Article
Nano-structures excited by light can enhance locally the electric field when tuned to plasmonic resonances. This phenomenon can be used to boost non-linear processes such as harmonic generation in crystals or in gases, Raman excitation, and four wave mixing. Here we present a theoretical investigation of the near-field phase matching of attosecond...
Article
We propose to use diabolo nanoantennas for experimentally investigating the origin of the enhanced third harmonic generation by localized surface plasmon polaritons. In such a geometry, the opposing apexes of bowties are electrically connected by a thin gold nanorod, which has two important functions in discriminating the point of harmonic generati...
Article
Full-text available
Nanoscale amplification of non-linear processes in solid-state devices opens novel applications in nano-electronics, nano-medicine or high energy conversion for example. Coupling few nano-joules laser energy at a nanometer scale for strong field physics is demonstrated. We report enhancement of high harmonic generation in nano-structured semiconduc...
Article
Full-text available
Plasmonic dimer nanoantennas can significantly boost the electric field strength in the gap region, allowing for a modification of the feed gap geometry by femtosecond laser illumination. Using resonant bowtie antennas to enhance the electric field of a low-fluence femtosecond oscillator, here we experimentally demonstrate highly localized reshapin...
Article
Full-text available
We experimentally demonstrate the use of subwavelength optical nanoantennae to assist the gentle ablation of nanostructures directly using ultralow fluence from a Ti: sapphire oscillator through the excitation of surface plasmon waves. We show that this ablation mechanism is the same for metal and dielectric. The analytical solutions of ablation th...
Article
Signal-to-noise ratio is a key factor in lensless imaging, particularly for low diffraction signal experiments in the single shot regime.We present our recent study of the noise impact on holography with extended references. Experimental data have been measured in single shot acquisition using an intense coherent soft X-ray high harmonic source. Th...
Article
Full-text available
High order laser harmonic generation is a relatively recent and promising source of intense coherent radiation in the extreme ultraviolet and soft X-ray domains. The process, due to the highly non linear interaction between an intense and ultrashort laser pulse and a gas medium, has a relatively low efficiency at the single atom level. However, pro...
Article
Full-text available
We demonstrate a method of using a Fourier holographic technique to utilize attosecond soft x-ray pulses to image nanometer-scale objects. A discrete frequency comb of laser-generated high-order harmonics, yielding a train of attosecond pulses, has been used to record spatially and spectrally resolved images. The individual wavelengths were also co...
Article
We report on the shot-to-shot stability of intensity and spatial phase of high-harmonic generation (HHG). The intensity stability is measured for each high-harmonic (HH) order with a spectrometer. Additionally, the spatial phase is measured with an XUV wavefront sensor for a single HH order measured in a single shot, which according to our knowledg...
Article
Full-text available
We present a setup for complete characterization of femtosecond pulses generated by seeded free-electron lasers (FEL's) in the extreme-ultraviolet spectral region. Two delayed and spectrally shifted replicas are produced and used for spectral phase interferometry for direct electric field reconstruction (SPIDER). We show that it can be achieved by...
Article
Full-text available
We present a study on the improvement of the spatial quality of a laser beam, called modal filtering,suitable to high-energy lasers. The method is theoretically compared with the classical pinhole filtering technique in the case of an astigmatic Gaussian beam, illustrating, in this particular case, its efficiency for filtering low spatial frequenci...